## or what’s the unit of area? How do I say that?

### Updated 04/09/2024 (thanks Tim)

This is what I’ve been missing to add in! You can’t now say this is wrong.

## 4 m^{2}

The diagram above shows four square metres or 4 m^{2}. If you looked at the length of each side it would be 2 m long! QED!

### Updated 13/05/2023 (see below)

**Metre** is the unit of **length** in the **SI system** and **square metre **is the** SI units **for calculating** area. **The confusion arises when we see square metre written or spoken. People cannot make out the difference between **square metre** and **metres squared** and assume they are the same, which they are not!

For example

If a square room has a length of 2 metres and is 2 metres in breadth, you can easily calculate its area with this formula.

Area= Length x Breadth | A=l × b |

2 metres x 2 metres | A = 2 m × 2 m |

4 square metres | A = 4 m^{2} |

The room has an area of 4 square metres, 4 m^{2}.

If you say that this is 4 metres squared what you mean is an area which has the length of 4 metres and you are multiplying it by a breadth of 4 metres which would give you an area of 16 square metres.

An Area = 4 metres squared |

4 metres x 4 metres |

16 square metres m2 |

So if someone asks you the correct area of the room mentioned originally, you should say that the area is 4 **square metres** or 2 metres square both of which are correct answers, but the 4 m^{2}, 4 square metres is standard.

- But beware more confusion arises as 1 m × 1 m = 1 square metres while 1 metre squared is also the same size as 1
^{2}= 1 metre square. You just get there by different routes.

Even though the unit looks like it is written as metres squared you pronounce it **square metre.**

Hope this clears any confusion you might have on this one!

Actually I ought to put a post script in!

**The same applies to volumes**

The correct SI unit for **volume** is **cubic metres**, (or in Chemistry they might use cubic centimetres). If you say metres cubed you mean that this is the length of one side and you need to cube this value to get the volume.

This cube could be described as **125 cubic centimetres** or 5 centimetres cubed.

I wasn’t sure that I ought to have posted this, but it looks like it is less well understood than I imagined, definitely my only popular post!

Just to show I am right, here is the page from the NPL site. The people in the UK responsible for measuring.

March 2024

For those in the US, here is the equivalent link https://www.nist.gov/pml/owm/metric-si/si-units-area

Thanks to Andy and Gareth Lewis Maths tuition for these additional thoughts.

Hi, the examples that you have given for metre square and square metre are incorrect.

2 metre square = 4 square metre (2×2=4)

2 square metre = 1 metre x 2 metre (1×2=2)

Andy

XxxxxxxxxxxxxxxxxxxxxxxxX

Good article. Andy’s alternative examples are also correct.

As well as the difference in size between square metres and metres squared (except when you have zero of each or one of each) there is a difference in shape. A metre square is a square with sides one metre in length – it refers to the shape and the side length, not the area. By contrast, a square metre is an area and can be any shape. A square metre could, for example, be in the shape of an oblong of dimensions 50cm x 2m, or in the shape of an A0 sheet, or 16 A4 sheets in any pattern.

After all the comments on here I decided to contact the people who know this stuff as metrology is their business.

So I contacted the NPL (National Physical Laboratory), this is

Andrew Hanson, MBE BSc (Hons) CPhys, Outreach Manager, National Physical Laboratory, Hampton Rd | Teddington | Middlesex | UK | TW11 0LW

**From P162 of the SI Brochure (most recent – 9 ^{th} edition 2019), the area unit definition is:**

**NAME: square metre**

**SYMBOL: m ^{2}**

**Almost certainly unchanged from when you first wrote your blog item.**

**As an example from the definition, spoken ‘9 square metres’, written ‘9 m ^{2}‘ are both 9 times the area of the unitary square metre.**

**The confusion arises from reading m ^{2} as the words ‘metres squared’. These words are NOT defined in the SI system. So with no formal meaning, ‘9 metres squared’ could indeed be taken to mean 9×9 m^{2} or 9 m^{2} – there is no definitive statement one way or the other.**

**I think that m ^{2} should be said out loud as ‘square metres’, so don’t take your blog item down, by all means say I agree.**

**Actually, if you just do the right/formal thing – use the words ‘square metre’ out loud and write as m ^{2}, and never, never even whisper ‘metre squared’, there is NO CONFUSION.**

**A formal way to do describe things with well defined, precise, scientific language avoids the types of problem you describe.**

**However, common parlance is commonly improperly used to describe scientific parameters, and these words without clear meaning cause confusion.**

**Most people don’t discriminate – though metrologists, and people who set and mark exam papers take care to get it right.**

**I am sure people passionate about English who know dictionary meaning of words are similarly riled by common misuse.**

For those in the US, https://www.nist.gov/pml/owm/metric-si/si-units-area

This post cleared a doubt of almost 25 years.thanks for your clear communication

Unfortunately, it is wrong. A square with one-metre sides is a ‘metre square’ NOT a ‘metre squared’.

No, a square with one-metre sides is a ‘square metre’.

Neither ‘metre square’ nor ‘metre squared’ are defined in the SI system, so arguing about which is correct is inconsequential.

it’s amazing how many retailers are not aware of the difference !

….And Science and maths teachers too.

Adrian Waygood is correct… this entire post has been based on the misconception that we are dealing with a maths problem, when it is in fact an English problem. “2 metres squared” is a nonsense phrase, probably from misreading the symbol “m2”. You either refer to “2 square metres” (an area) OR you refer to “a 2 metre square” (a shape, which equals 4 square metres). There is no time when you can say “metres squared” or “squared metres”.

I agree Jeff but listen out to how many people do indeed say metres squared- dare I say the majority!

The initial question was raised by the printed labels on items for sale,

Which is very confusing when speaking to sales staff.

My gaffer posed this question when I was a joiner apprentice.

I think one of them is ..1 m x 1 m. The other, is I think 333.333 mm x 333.333 mm…? As (for simplicity) if we take .999mm x .999 mm, & multiply together..it comes out as virtually 1m square. Whereas..1m x 1m = must be more square metres…. as it’s 3 times the size ?

1m x 1m is exactly one square metre.

.999mm x .999mm doesn’t come out as virtually a 1 metre square because .999mm is less than 1mm, so you’re talking about a square that is almost 1mm x 1mm.

.999m x .999m does come out as virtually a 1 metre square.

It’s very easy to mix up metres and millimetres when they’re abbreviated.

Opps! Slip of the finger! I ment .999m x .999m.

Doesn’t matter if that is what they say – they are wrong. How many times do people refer to feet squared? Never, because they have always known X square feet as a measure of area even when it is written as ft2. The problem is that metric has been badly implemented in the uk and everyone thinks this weird m2 abbreviation must be a literal metric thing. The system has never been embraced and has been appallingly taught. We still hear bbc commentators refering to “1 metre and 20” (20 what) as if it is ok to mix units (it’s not) as was done with imperial feet and inches, lb and oz etc. It shows a lack of a fundamental understanding of metric. I could go on for days about this!!

Yes it’s like the weather forecasters giving the temperature in degrees, a unit of angle!

The original question was raised when shopping for material, some shop sold it as £ 10.00 for 2sqM another sold it as £ 10.00 for 2Msq,

Which is cheaper, the first or second shop?

Exactly! Or like how people mispronounce “kilometre” as “ki-LO-me-tre” (like “thermometer”) instead of as “KI-lo-me-tre” (like “millimetre”). There are very few places in the world where the SI is properly taught. Most people in the UK don’t even seem to know that the space is required between the quantity and the unit symbol, and most major newspapers (BBC, The Guardian, etc.) explicitly resist following the proper way, which exacerbates the problem.

What’s wrong with saying, “1 metre and 20 (centimetres)”? It’s just a spoken abbreviation and everyone knows they mean a further 20cm, not a further 20m.

….yet it is far more common to hear acceleration expressed in ‘metres per second squared’ rather than ‘metres per second per second’ ( my preference). This is so widely used, it seems rather pedantic to argue against ‘metres squared’. However there most definitely IS a difference between a ‘metre squarED’ and a ‘metre SQUARE’…. the former being an area and the latter a shape.

Lionel Adrian WAYGOOD, you were incorrect and now you are ‘straw manning’ (changing the argument) to claim another concept is misused so it’s ok to misuse this too.

But, no, “metre square” is incorrect, it’s “square metre.” Also, saying that your imaginary “metre square”, as you incorrectly call a square metre, is a shape and not an area is misleading, as a square metre obviously has an area too, of 1m².

Thank you Jeff . Now I will confidently use square metres as area or metres square which refers to the dimensions of the shape.

Do not listen to Jeff, as they said Adrian was correct, when he wasn’t.

But, if you “use square metres as area” you’d still need to not confuse the numbers as dimensions. You need to see square metres as individual pieces. Also, “metres square* which refers to the dimensions of the shape” – *that’d be ‘squared’, as in Maths, to multiply by itself, and the only shape it could be is a square.

But in Maths “squared” means to multiply a number by itself. So, “2 metres squared” means 2×2, and equals 4 square metres (4 m²). Unless you are seeing a square metre as a physical object, like a rug, which can’t be used in a sum, but that’d have some height too, whereas a metre square is 2 dimensional, so can’t exist physically.

But, everyone is missing the point. The point of the article is that a square metre (m²) is always a square with 1m sides (1m²), so 1m x 1m (or 100cm x 100cm, and 1000mm x 1000mm). So, if you have 9 square metres you can see it as 9 individual squares of 1m², so if you had 9 m² of rugs you can place them as a 3×3 square, or a 1×9 long strip.

The article is trying to highlight the error of people thinking, e.g. 9 m² (“9 square metres”) is “9 metres squared” and that “squared” means the 9 must be multiplied by itself, 9×9, and therefore would equal 81 (81m², “81 square metres”), when 9m² just means 9 square metres, where there’s no Maths to be done.

*Adrian Waygood is not correct.

Hi, the examples that you have given for metre square and square metre are incorrect.

2 metre square = 4 square metre (2×2=4)

2 square metre = 1 metre x 2 metre (1×2=2)

Hmm, I agree with you Andy. But this is where the problem starts 2m x 1m = 2 square metres but we agree that a square of side 2m x 2m would be 4 square metres (4m

^{2}) that is why it is better to use the correct term and use square metres for area! Thank you for your help! What would you say to a square of side 1.414 m?I would say, that’s 1.9993966 square metres

🤣🤣🤣🤣 I asked for that! Do send me your precise equipment for measuring to this level of precison!

A simple calcalator on my phone, just the two values timed.

Good article. Andy’s alternative examples are also correct.

As well as the difference in size between square metres and metres squared (except when you have zero of each or one of each) there is a difference in shape. A metre square is a square with sides one metre in length – it refers to the shape and the side length, not the area. By contrast, a square metre is an area and can be any shape. A square metre could, for example, be in the shape of an oblong of dimensions 50cm x 2m, or in the shape of an A0 sheet, or 16 A4 sheets in any pattern.

The problem is trying to find out what is the legal aspect of ordering something that is written as 2 m squared and then recieving something that is only 2 square meters ?

If I was the customer I’d want it clear in the order.

I think I need another blog post on why it is written and said differently.

So what is the answer, the first or second shop?

Urgh I just wrote a massive reply and my phone gave up and the message disappeared. I’ll try again.

So carpet company 1 sold for £10 2 square metres. That would be a piece of carpet 2m by 1m or 2m2. The other company were selling carpet at £10 for a piece 2 metres square so that is carpet 2m by 2m so this is cheaper. However I think both companies probably think they are selling carpet for the same price and would you want to buy carpet from a company that don’t understand area despite it being part of every transaction?

Personally I’d ring up your local trading standards people and ask where you’d stand. I’ve always found them really helpful. If you bought carpet and they wouldn’t refund it I would think you have a good case with trading standards if you can prove it. Best wishes and let me know how you get on.

Exactly!!!!

I purchased some liquid fertiliser and the instructions indicated that the 9 litres was to cover 10 sq m. The distributor advised that it meant 10m x 10m & not, for example, 5m x 2m. So if the former is correct, what does the latter mean?

sq m is dubious. I’d say that was meant to be 5m x 2m. If he really meant 10m x 10m it ought to say 10 m sq or. I thought they were making it clear that it was m2 but to clear it up they wrote it out as square metres, which is how you pronounce m2. How did the liquid fertiliser do? The latter would be 10 m2, pronounced ten square metres.

9L is about the size of a watering can, and assuming the “liquid fertiliser” was actually just 2 cap-fulls to be diluted with 9L of water in the watering can each time I’d guess it’s more likely for 10 m² than 100 m². However, if it wasn’t to be diluted it’s more likely for 100 m², as that’d last you 10x longer, as 10 m² would use it all up on one small patch, and fertiliser’s usually needed every 2 weeks in the garden.

I completely disagree. ‘2 m square’ or, more correctly, ‘1-m square’ describes a shape… in this case a square having sides which each measure 2 m. So, a ‘2-m square’ has an area of 4 square metres (often spoken as ‘4 metres squared’. So ‘metre square’ is NOT the same as a ‘metre squared’.

I will stand by this article that the SI unit of AREA is m2 which is pronounced square metres. This is the point. Everything else is not SI units. To say it as metres square is incorrect and leads to confusion. PERIOD

Thank you for engaging with this article.

https://www.nist.gov/pml/owm/metric-si/si-units-area

https://www.npl.co.uk/si-units

“So, a ‘2-m square’ has an area of 4 square metres (often spoken as ‘4 metres squared’. So ‘metre square’ is NOT the same as a ‘metre squared’.”

LOL still commenting and now even confusing your own terms. No, 4 square metres is never correctly “spoken as 4 metres squared”, as that’d be 4×4 = 16 m², not 4 m².

At least you’ve learnt it’s ‘square metres’, and not ‘metre squares’, which is gibberish.

…Why is the shop even using units of 2 for £10, it makes no sense, like 1 would cost £6, not £5, so it’s better value, but I think the minimum order for carpet is 10 m² anyway (you could buy 2 m² but they’d charge you for 10 m², or something).

If the square is 4 square meters why have you put it as ( 4 meters squared)

That’s the point. It is written as m2 but said as square metres.

That’s the point it is written in a different way to how it is pronounced.

How can it be written different to how it is written ?

2m x 2m = 4m2 “4sqm”

4m x 4m =16m2 or (4m)2

“4metre sq.”.

I think you are confused! The first is area the second is length, breadth and shape.

Read the question again

Your explanation of M2 v square meters is total gobbledygook

I’d agree with Andy k for his/her explanation that the correct basis of examples are the 2m x 2m = 4 square metres. “Not a 4 metres square” because the 4 metres square is the only measurements of length sides, Then the 4m x 4m = 16 square metres which is the whole wide sides has a 16 squares divided from 4 metres squares

I always thought that to write 4 square metres,

It was written as 4 sq mtrs ( 2×2 ) = 4

And 4 mtrs square is written as 4 mtrs 2. (4×4) = 16

This is correct

This is not the SI (Standard Internationale) the world standard of writing out square metres and metres squared. The SI symbol for m is m and m^2 is square metres.

This is not the SI way of writing things out, but yes it has been written out like this when buying a carpet for example.

”I always thought that to write 4 square metres, it was written as 4 sq mtrs ( 2×2 ) = 4”

Square metres, sq m and sometimes sq mtrs are all used to denote the same thing, a unit of area. The symbol for that unit is – by international agreement – m followed by a superscript 2, which admittedly looks like it should be pronounced “metres squared” but is actually still pronounced “square metres”.

“And 4 mtrs square is written as 4 mtrs 2. (4×4) = 16”

A square with side length 4m can be described verbally as “4 metres, squared” but not “4, metres squared”. The latter would suggest that there is a unit called “metres squared” which doesn’t exist (it’s just the symbol for “square metres” looks like it should be pronounced “metres squared”).

In symbols, it’s (4m)^2, not 4m^2 which is pronounced 4 square metres and is only a quarter of the size.

For those familiar with PSI for measuring pressures in tyres and so on, PSI stands for “Pounds per square inch”. It’s not an SI unit, but follows the same convention when describing the area. It doesn’t matter whether you measure in mm, cm, m, inches or anything else, the corresponding units of area are “square units”, never “units squared” despite the confusing symbols. Some teachers when challenged attempt to justify using the name ”metres squared” for areas by claiming that they do it differently and it’s an alternative. It’s not, it’s wrong.

The International System was set up so that we all use the same units, names, symbols etc. For area that means square metres. I’m happy to dig out my screenshots from the BIPM if necessary.

This not straightforward. It’s a bit counterintuitive and I have sympathy for the many students – and many maths teachers even – who get it wrong.

As well as wanting students and teachers to learn and follow the established international convention in this case, I find that students tend to understand the subjects of area and volume better when they do.

this article is wrong!

That isn’t a helpful comment! In what ways do you think it is wrong. I don’t like fake news so only publish what I deem to be correct. What is your background that tells me that I am wrong. I am happy to discuss this.

Edward Murphy is quite correct. You are wrong. You are confusing ‘metre square’ (an square having sides of 1 m), with ‘metre squared’ which can have sides of any dimension giving that area. They are completely different. The SI symbol, ‘m (raised to the power of 2)’ is correctly spoken as ‘square metres’, but it is also correct to speak it as ‘metres squared’. My background? Electrical engineer, engineering lecturer and author, masters degree.

Just to say this article is NOT wrong. I don’t know who taught you maths but check out the correct SI unit for Area from the NPL- these are the people who deal with measurements.

Sorry, blog, but the article IS wrong. Period! I have written extensively on SI, including the recently introduced new Base Unit definitions. Athough many people pronounce ‘square metres’ as ‘metres squared’, I prefer the former. Having said that, an area measuring 1 m by 1 m is commonly spoken as a ‘meter square’ to describe its shape, or a ‘meter squared’ (or ‘square metre’) to specify its area. When describing acceleration, many people say ‘metres per second squared’ although, I prefer ‘metres per second per second’.

LOL still going? The article is correct, you are wrong. You don’t even agree with yourself: “Athough many people pronounce ‘square metres’ as ‘metres squared’, I prefer the former.” – back in 2019 your original post only states (the gibberish) “metre squares.”

Also, no one correctly refers to square metres (m²) as “metres squared”, as that would mean you then need to multiply it by itself further, giving an even bigger number/area.

“Metre squares” is gibberish English – the unit (metres) comes second.

You are even now saying “meter squared” – you are clearly confused enough without using electric, gas, or parking meters as a unit! Why not just stick to using metres?

Ok. All this article is about is the mispronounciation of the unit for area. The unit of area is m². This is pronounced “SQUARE METRE”. Check out the NPL or US standards and measures websites. They are the people who are the authority on this. It doesn’t matter if you are a maths teacher, student, carpet fitter, surgeon. The unit of area is the square metre.

Holy smokes, please take this down, before it gives people the wrong info.

I beg to differ. This is not wrong and it is not scientific to show the difference as Ken has shown, although perfectly OK in ordinary everyday life terms.

What is your background that tells me that this is wrong?

Edward Murphy, the original article is correct.

There is an international consensus documented by the Bureau International des Poids et des Mesures (BIPM).

If you don’t know, please don’t rubbish a good article on a difficult subject. BIPM have a website and the info is on there. It’s displayed on my Patreon page too if that’s easier. Nobody remotely serious in science would contradict the BIPM on this subject.

Gareth Lewis

B.Sc. MathStat (Warwick)

Thank you for posting this and so promptly. I appreciate this.

No problem. It can be so counterintuitive that students often don’t believe me if they don’t know me well already. Having experienced the disbelief myself – even in schools where other teachers joined in with the disbelief – I had to help.

There is no such debate in scientific communities.

You are both confusing ‘metre square’ and ‘metre squared’ -completely different. If you are describing an area measuring 3 m by 3 m, then you would say a ‘3-m square’. But its area is ‘9 m(raised to the power of 2)’, spoken EITHER as ‘nine square metres’ (my preference) or ‘nine metres squared’. Similarly with cubes: a ‘three-metre cube’ is a cube having 3-m sides’, but its volume is ’27 m (raised to the power of 3)’ spoken EITHER as ’27 cubic metres’ or ’27 metres cubed’.

Further to my comment, how would you express the unit for acceleration? It’s written as ‘m/s(raised to the power of 2)’, and it’s correct to speak it either as ‘metres per second per second’ or, more commonly actually, as ‘metres per second squared’. The same rule applies to ‘m (raised to the power of 2)’ -it can be spoken as ‘square metres’ OR as ‘metres squared’ (but NOT ‘metres square’, which is something completely different! Once again, I argue that you are confusing ‘metres squared’ and ‘metres square’.

While your logic would make sense in the interest of consistency, pronouncing “27 m² ” as “27 metres cubed” is actually incorrect as per the SI because it is defined as “cubic metres”. This has to do with the fact that geometric units (areas and volumes) have the adjective before, while non-geometric units have the past participle after the underlying unit. This is why, for example, nobody pronounces “9.8 m/s²” as “9.8 metres per square second” because conceptually, a “square second” doesn’t make any sense, but a “second, squared” does. It’s just one of those exceptions in the SI.

1 square metre is completely different from 1 metre square(d). Not in actual area, but in shape.

1 square metre could be .5m x 2m, or .25m x 4m

1 metre square(d) is 1m x 1m.

Completely different though when it is 2 square metres against 2 metres square(d). One remains 2 square metres, the other is 4 square metres.

At least, that’s what I was taught at school before I left in April 1973 aged 15. If things have changed in the ensuing almost 48 years, I have no idea.

And before I forget, to forego any further confusion as to what is what, 1 square metre should be written down as 1sqm, 1 metre square(d) should be written 1msq. Preferable it should be written out fully, but what would I know, leaving school at age 15?

No the unit of Standard International Unit of AREA is m2, where the 2 is a superscript!

Not quite true. The SI derived unit for area is the square metre (at least in English, it may be translated in other languages), and m with a superscript 2 is the symbol for that unit, and such symbols are used internationally, regardless of local language. I’m not aware of any language in which the word for metre doesn’t begin with an m, but for example, in Italian, the word for kilometre begins with a c, but km is still used as it is the internationally agreed symbol for kilometres.

There is an argument for stating units fully, as is often done in medical contexts to avoid confusion, but using, say, “square metres” is not the convention because it is language-specific, whereas m superscript 2 isn’t.

The SI unit of area, Standard Internationale is the square metre m2, where the 2 is a subscript. If you don’t believe me read the comments from the education officer of the NPL. sqm is NOT a recognised scientific way of writing area.

No, the only things that’s changed it seems is that nowadays, on this topic, many teachers in the UK have no idea.

Well as a teacher I’m a bit offended and I’m sure there was ignorance is previous generations.

That’s true, but as an example, I was training prospective teachers to pass the QTS Numeracy Skills Test and regularly encountered student teachers who, for example, didn’t know how many pence there were in a pound. I can’t speak about other subjects, and for sure there will still be some great teachers, but the decline in standards in Maths is as clear as day.

I’m still yet to discover the minimum qualification in Maths required to teach Maths, but several of my students have claimed that their Maths teachers don’t have a C in GCSE Maths. I didn’t believe them at first but some of the mistakes I’ve seen are just so basic that I’d be disappointed if they were from my students, never mind a teacher.

Unfortunately in the UK the priority seems to be maintaining a ratio of students to teachers, with inevitable consequences in quality control. The salary doesn’t encourage the best mathematicians to consider teaching either.

Well if that is your experience then it is quite sad. Please note though that the UK doesn’t have one education system. In Scotland to teach Maths you’d have to have a degree or covered the subject for 2 years at degree level, although this is only for maths. My niece has just started teaching in England and she had excellent grades in Maths and further maths A level and did an economics degree.

The students I’ve taught in the last year don’t appear to know that you turn to the next empty page when continuing with work, choosing instead to start writing at whichever page the jotter falls open. Some students ask for a jotter most periods and when asked “Where’s yours?” I have had the reply “in my bag, but I can’t be botered to get it out!”

Maybe after covid19, all teachers will be replaced with Google Classrooms and Microsoft Teams and a few computer programmes.

Hmm, SO confusing!!

Wikipedia says the sq m is annotated m^2, (Where ^ indicates superscript) which goes against my personal grain (which agreed with your initial article), but if I work it out Wikipedia makes sense.

It’s important to know whether we’re squaring the unit itself or the number of units.

Or BOTH.

If it’s m^2 then it’s a square unit, not a square of the number of units.

so: 2m^2 is two single units of cloth.

However, if I square the units (2^2 M) is four linear metres… with no area at all.

In order to get four square metres you would have to square both, the unit AND the quantity: it’s 2^2M^2

So… according to Wikipedia a square metre is always a metre squared, not the square of the number of units.

To go off following a fancy:

This means 100 sq cm remain as 100 little squares = 100*1cm2 equals one linear metre only a centimetre wide.

However…

In order to get a square metre you would have to square the NUMBER of units AND have squared units,

Because 100^2 cm= 10,000 cm but has no area…

so 100^2 cm2 or 10,000cm2 is a square metre but 100cm2 ISN’T.

I’m a cartoonist not a mathematician. Am I as confused as I feel or have I just made sense?

Thanks for your contribution to the debate Brendon, and I am certainly more confused by the middle bit of your post! m2 is the unit of AREA and could be your 100 cm x 1 cm squares or it could be a square of sides 10 cm, as 10 cm x 10 cm = 100 cm2. Area can be any shape. You don’t square the m2 by m2 Oh yes I’ve just read your post and the last bit makes sense and yes totally correct. There are indeed 10 000 cm2 in 1 m2.

Now as a cartoonist, your task is to explain that to the world! This is by far the most popular post of my complete site, so see what you can come up with and hopefully you can get some commissions, should you require them. I’ve seen text books that say metres square instead of square metre (m2) I’d love your interpretation on something that obviously causes lots of trouble with students and the general public. Keep safe!

If I’m understanding correctly, I think the confusion is that it is written differently than it is said. This shouldn’t be too foreign, however, as currencies always have this dissonance (e.g., “$5” is read as “5 dollars”). However, the issue here actually only applies to geometric non-linear units (i.e., areas and volumes). Because powers of 2 and 3 make sense geometrically, they are exceptions to the rule of reading units as ” squared” or ” cubed”. Thus, geometric units are read “square ” and “cubic “, but they are written the same as other units nonetheless. For example, “5 m²” is read as “5 square metres”, but “5 s²” is read as “5 seconds squared”.

There is no such thing as “sq m”, “sq cm”, or any of the myriad other abbreviations. The SI doesn’t allow abbreviations (https://www.bipm.org/utils/common/pdf/si-brochure/SI-Brochure-9-EN.pdf#page=33), as it uses symbols exclusively. They’re like the per cent symbol (%); they never change based on language, whether the quantity is greater than 1, or based on upper- & lowercase.

Great post and am in complete agreement, but surprised how little material there is online about this surely common mistake.

The SI brochure states only that”square metre” is acceptable, however the following website (American but trustworthy…) does say for powers, the unit can be said before or after the power. I still think it’s a little ambiguous and the examples are not extensive enough. I think it also raises the possibility of metres square vs metres squared…? It’s not just phonetics here, metres squared and square metres are two different things, assuming the preceding number is greater than 1

https://www.nist.gov/pml/special-publication-811/nist-guide-si-chapter-9-rules-and-style-conventions-spelling-unit-names

Thank you for a great blog

Thanks Tom, it’s a shame there isn’t a more widely known website on which to discuss it. Talking to other teachers I think they are not all aware, but I try to correct them.

So what is the abbreviation symbol for metres squared?

3m x 3m is 9 square metres or 9m^2

So how is 3m squared annotated? How do you write that as exactly 3 metres by 3 metres or 3m squared, which incorrectly in my mind should be 3m^2? Would it be (3m)^2?

Yes it’s (3m)^2, which has an area of 9 square metres. Note though that 9 square metres indicates the area, not the shape. For example 9 sheets of A0 paper would have also an area of 9 square metres, even if they’re not arranged in the shape of a square.

Which, when the brackets are squared= 9m^2 😃. Got it.

Correct 😊

Sorry I meant “symbolise” not “annotate”.

Having thought about it, it should be (X)^2 m ?

That’s the problem. There is no correct way to say this. It cannot be (X)^2 m as m is the SI unit for length. Read the comment by Andrew from the NPL. These are the people tasked with defining measurements. I would say it is 3 metres squared, but this is a personal opinion and there is no correct value apart from 9m^2 said, nine square metres! Thanks for your comments Richard. It is a very interesting debate.

Thank you for linking to this site, hopefully I can write other interesting blog posts!

M² vs SQM

There is a difference between m² and sqm and it isn’t complicated.

Area is calculated by multiplying length by the width. If a room, for instance, is an odd shape, you divide the room up into various rectangular shapes and add them together to get the total sqm NOT m².

It is too confusing to just use examples with the same length and width. It’s easier to understand if you use varying lengths and widths e.g. a 5m x 7m room would be 35sqm NOT 35m² because 35 m² means multiply 35 by itself (that’s what the 2 means) which would give you an area of 1,225sqm.

So, use “sqm” when giving the total area AFTER various calculations of length x width have been determined.

I disagree! there is no SI unit of area that is the SQM, it is a way of saying it correctly, but the SI (Standard International) for area is the m2, 5m x 7m room would be 35m² (5 x 7 =35, m x m = m2)

I don’t know what country you are in but here is the proof https://www.nist.gov/pml/weights-and-measures/metric-si/si-units-area#:~:text=The%20SI%20unit%20of%20area,which%20is%20a%20derived%20unit.

Here is the great website for the UK https://www.npl.co.uk/si-units

As you can see the unit of area is defined as the square metre, written as m2!

Oh and Dara, if you’re in NZ here is the proof from there https://www.measurement.govt.nz/assets/Uploads/MSL-SI-Concise-Summary-A4-Web-Doc-03.pdf

Thanks for getting in touch and hopefully you’ll believe me. I agree that SQM is the way it is pronounced, but not the way it ought to be written.

“So if someone asks you the correct area of the room mentioned above, you should say that the area is *4 square metres* both of which are correct answers.”

Surely it’s either 4 metres squared, or 16 square metres?

True but as there is ambiguity in the 4 metres square and this isn’t a standard Internationale unit, so you’d be better sticking to 16 square metres. Thanks for your contribution.

Exactly, so why have you said “4 square metres”? Isn’t that wrong?

Square metres is how you say it metres square is how it is written.

But 4 metres squared can be used for a square of side 4 m as you would square that length to find the area.

Let’s just hope teachers are better informed and teach it properly!

That’s not correct. A square of side 4m is 16 m2… you even said it yourself.

“if your square has a length of 3 meters and a width of 2 meters, then 3 x 2 = 6 m2.”

https://www.techtarget.com/whatis/definition/square-meter-meter-squared#:~:text=The%20square%20meter%2C%20also%20called,sometimes%20abbreviated%20as%20sq%20m.

Yes, for metres squared, but you said square metres. A square of side 4m is 16 m2.

“if your square has a length of 3 meters and a width of 2 meters, then 3 x 2 = 6 m2.”

https://www.techtarget.com/whatis/definition/square-meter-meter-squared#:~:text=The%20square%20meter%2C%20also%20called,sometimes%20abbreviated%20as%20sq%20m.

I think we are at Cross purposes and I think we agree. What I am saying is that m2 is pronounced square metres. Many people don’t appear to appreciate this.

Exactly, so this sentence is wrong:

“ So if someone asks you the correct area of the room mentioned above, you should say that the area is 4 square metres both of which are correct answers.”

You should’ve said 4 metres squared in this case.

Thank you Joe. I see what you mean. I hope I’ve fixed it now.

I have just found this on instructions for spreading grass seed. sow 50 gms per square metre, to do this mark out 1 metre squares with canes. This from suppliers?

That would work because you are marking out a square 1m x 1m which is both 1 square metre and 1 metre squared! I think this is actually correct. Hope the grass grows well, and that you’re not sowing in this heat.

Not so fast, I have been measuring areas for materials for many years. 5oomm x 200mm is one square mtr or 100,000 2mm. One metre square has 1000,000 square mm, so can not be the same size.

500 mm x 200 mm is not 1 m2. Convert this to metres, that is 0.5 m x 0.2 m that is 0.1 m2. There are 1 000 000 mm2 in 1 m2 as you’ve noted. Going back to the mm there are 1000000 mm2 in 1m2 so 500 mm x 200 mm is 100 000 mm2, which is indeed 0.1 m2.

I do believe you are mixing square mtrs with mtr squares. By the way I was moored on the Bridgwater at Worsley for many years. That was when red was 200ltrs for about £50.00.happy days.

I am sure I am right on this one. Contact the NPL m2 is said square metres.There are one million square mm in one square metres.

Bridgewater is lovely! We do have the Falkirk wheel though