I was taught in the mid-90s not to use cm.

I use mm generally, it keeps things simple at work and annoys the wife at home.

mils are milliradians, so a unit of angles, just to confuse things a bit more.

I build buildings entirely in mm.

My bike has 150mm forks and a 5″ rear shock 🙄

When you buy timber, very often it’s bought in Imperial, because it’s imported from the States etc,.

Standard timber sizes are based on un-machined size in imperial units – doesn’t have to be imported.

Annoyingly sheets are in imperial

Not always (quite unusual around here) – A few years ago I put up framing for a stud wall based on 8′ x 4′ sheets and ordered the same from the BM. Fixed the first sheet and thought my first stud was a bit out. Went to fix the second sheet and it missed the stud completely – the sheets were 2400 x 1200mm, not 8′ x 4′. BM’s response: “Yes, they’re metric eight by fours”.

We also get the ‘Mil’ = 0.001″ and “Mil” = mm confusion with ‘murricans. They often use both senses in the same conversation.

Centimetres are for dressmakers only 😉

I’ve seen volumes quoted in dm^3 which is an even weirder unit save that it is 1L so keeps the nomenclature of the units in check. I’ve yet to understand why in some applications at work we measure things in McP (megacenti-Poise).

cm works in plenty of applications. Accuracy to mm not needed/possible and values of less than 1m being and example.

I use a horrible mix of measurements, depending on what I’m measuring.

+1

Same with weights, and liquids.

Not always (quite unusual around here) – A few years ago I put up framing for a stud wall based on 8′ x 4′ sheets and ordered the same from the BM. Fixed the first sheet and thought my first stud was a bit out. Went to fix the second sheet and it missed the stud completely – the sheets were 2400 x 1200mm, not 8′ x 4′. BM’s response: “Yes, they’re metric eight by fours”.

Plywood is pretty much always in full imperial sizes – but OSB is a devil for this. Different thicknesses of OSB from the same manufacturer / supplier vary between full 8×4 (2440 x 1220) and metri-perial (2400 x 1200). Plasterboard tends to be metri-perial too.

I’m a professional measurist. I measure, therefor I am.

My favourite unit of measurement is the gorota / yojana (two languages, same thing).

The gorota (yojana, etc.) is defined as ‘the distance over which you can hear a cow moo’…

I use decimetres ‘cos I’m cool & edgy.

Measurment and precision are 2 very different things, cm is a perfectly valid unit and useful for a lot of things, must be those imperial simpletons who can’t remember to x or / by 10.
For instance there are very few occasions where I need to know your height in mm as unless I’m going to use a laser to cut your hair it an be too precise though by using a decimal I can magically express it as the same number.

i use cm a lot but I am a foreigner . 😉

There are two basic metric systems – CGS and MKS. MKS is the more usual one (also known as SI).

Looking into CGS units of measure – I now have a new favourite.

‘A Darcy’ is a unit used in the measure of permeability. And not, as I had previously been led to believe, a unit of bra size or of the frequency of appearance of bravissimo adverts.

I’ve yet to understand why in some applications at work we measure things in McP (megacenti-Poise)

‘Cos the Poise is the preferred unit for viscosity for loads of industries, but it’s based on the dreaded centimeter 😀 (the CGS unit system), and it’s a factor of 10 different from the same measurement in SI units (1 Poise = 0.1 Pascal seconds), offering endless scope for wrong things to happen.

My industry has have ended up using deciPascal seconds so that the measurements are numerically the same in SI units (1 dPa s = 1 Poise). I guess your industry has gone the other way : 1 centiPoise = 0.001 Pa s)

So you could have mega-Pascal-seconds (MPa s) instead of megacentipoise, but I guess everyone associates centipoises with viscosity and expects to see those units – I guess you probably know this 😉

I have customers who ask for signs in the universal measurement unit which is the A4 piece of paper.
Yep, half A4 sized sign please, or twice the size of an A4 please…
In these cases I would prefer cm’s or inches.

I glad someone has raised thus important units issue. As said before if some gives me a size in cm I don’t trust it as they’ll likely have no engineering / practical knowledge.
I have no idea how the US functions in inches, its so backwards. Mind you other Europeans probably think the same of us using miles for driving. And WTF is car consumption here measurement in mpg still, I don’t even know how many litres are in a gallon!

There’s no litres in a gallon, just 8 pints.

Imperial gallon or US gallon?

I glad someone has raised thus important units issue. As said before if some gives me a size in cm I don’t trust it as they’ll likely have no engineering / practical knowledge.

Does it matter though? If all other units are in cm to quote in mm is just being an arse. How much precision do you need? My KS Lev asks for a specific mm of cable showing at the point where it is clamped for very good reason, other times a few cm is adeqaute to convey the required information.
Convention has led to certain units of a fantastic system where conversion is as simple as moving a decimal place. I have building drawings in mm FFS, all I need it the length KM would probably do. There seems little need measuring a screen size in mm unless it’s a tiny phone or super critical (may be when ordering a cover or glass but not so much when comparing 2 TV’s in a shop)

4.55 or 4.45 US IIRC

How many hp to a PS?

Inches really screwed my head when doing my apprenticeship was told by the tradesman to cut stuff in inches “cut it 6 3/8″ loon ” WTF is that in mm?

I was the same, metric in school but all my tradesmen were in their 50s and 60s. I now work imperial all the time and if something pops up in mm i have to convert it in my head, I just seem to have a mental block with metric these days.

I work in a college as a technician and get a lot of students from other courses coming and asking me for mdf etc cut to size.

Always weird getting 16 year olds asking for stuff in inches… Where’d they get that from?…

Do they just think I’m old enough to need it written in inches to understand it? 😆

I don’t get the cm hate – and I’m an engineer (there, I’ve said it), so the only correct unit of linear measurement is the m if you want to get all snobbish about measurement units. As already mentioned above, a cm is a fine unit if that’s the required precision. Clearly if you require mm precision then it’s silly to use decimal cm, but then are the metric-imperial 8x4s discussed above actually 1200mm long rather than 1199mm? TBH if you’re a decent engineer (or tradesman) you should be able to cope with converting units if you’re working in a country which still uses a mix (though thankfully if you’re working in engineering you don’t get the mess they have in the US and imperial is nowhere to be seen – even if when I did engineering workshops the instructors still talked about thous when all the machines were metric). I’m not sure how much I’d trust somebody unable to cope with a cm measurement – if I’m asking for something 45cm long it’s because I don’t care that much if it’s 449mm or 451mm.

Hmm, isn’t half A4 A5 and twice A4 A3? If it helps at all half A4 is 0.03125m² and twice A4 is 0.125m² 😉

A4? Bring back the old imperial paper sizes. Double Elephant anyone?

As mikewsmith says, I don’t get the problem with cm…..

If I’m measuring up for a bit of DIY, I’ll probably use cm to gauge how much board I’ll need to cover a panel, for example. So, going to B&Q with a note that says I need a piece of MDF to cover at least 152x87cm is perfectly valid. I know in my head that it’s 1520x870mm or 1.52×0.87m but for the size concerned 152×87 is sensible in my head.

When I get it home & need to trim it to size, I’ll then measure & cut to mm.

It’s just using the appropriate measurement for the task.
Obviously you need to be careful if there are industry/company standards. At work, I wouldn’t create a drawing in cm because everything is done in mm.

All this talk of not trusting someone to know what they are on about unless they are dealing in m or mm is nonsense.
At previous places I’ve worked, you’d look like a bit of an idiot if you stuck to m or mm, where nozzles were measured in microns & drop size measured in picolitres. If you started blurting things out in mm & litres it wouldn’t really be appropriate. A drop landing accuracy of 6 microns is a lot more sensible than 0.006mm.

Going back to my original post it was about the building trade eg, 1.550 or 1550 but definitely never 155 or microns or even chuck in a decametre look that one up.
I will stick, cms should be dropped like the 1p

I’ve yet to understand why in some applications at work we measure things in McP (megacenti-Poise).

I had to Google that one.

Really wish I hadn’t now. My head hurts.

As said before if some gives me a size in cm I don’t trust it as they’ll likely have no engineering / practical knowledge.

Eh? I’m not in ‘the trade’ but wouldn’t you just use the different units as needed/appropriate? I don’t see what’s wrong with saying 76cm rather than 760mm if that’s what the figure is.

Is it more that in your line of work numbers that can be converted to cm with no loss of precision are rare?

All this talk of not trusting someone to know what they are on about unless they are dealing in m or mm is nonsense.

Its not nonsense or snobbery its lived experience from people who make things – in your own example your giving size to the nearest whole centimetre. Thats fine if it its ‘enough to cover’ in which case a CM is a reasonable roughcut to work from – but a whole centimetre is a large margin of error for something that has to fit.

I’m not in ‘the trade’ but wouldn’t you just use the different units as needed/appropriate? I don’t see what’s wrong with saying 76cm rather than 760mm if that’s what the figure is.

Using different units depending upon “feel” means that you have no common ground, and nothing makes sense. Building are designed in millimeters, if you were to dimension them in mm, cm & m then you’d not be able to build it.
I’ve taken people out on surveys and ended up having to take the tape off them and make them hold the dumb end because they a) can’t read out numbers properly, and b) aren’t consistent.

Building are designed in millimeters, if you were to dimension them in mm, cm & m then you’d not be able to build it.

Why couldn’t you, if the numbers are correct and units are given rather than assumed?
More seriously, I take your point that in practice that’s obviously not a good idea. If your field has a standard then you might wonder what’s going on when someone doesn’t follow it.
But saying you would assume someone has no practical knowledge if they use cm still sounds a but much to me.

All this has got me thinking of Spinal Tap’s Stonehenge 😆

Why couldn’t you, if the numbers are correct and units are given rather than assumed?

You could, but if I were you I’d add a large piece of risk to cover the mistakes and re-ordering of stuff that doesn’t fit.

Hmm, isn’t half A4 A5 and twice A4 A3?

That was the point!

Like ahwhiles I’m a professional metrologist, working in calibration and testing laboratories for ‘ahem’ years. It doesn’t bother me what units you want it in. I’ll measure it how I want and oonvert.

What really annoys me is people arguing that Lbf.in is the same as inlbs. Wee at simmering point…

Don’t get me started on people who don’t know that measurements should be stated WxHxD. Had to work on a client document today that had all 3 ways as well as CMs mixed with inches. I don’t trust that any of it is correct. Idiots

The gorota (yojana, etc.) is defined as ‘the distance over which you can hear a cow moo’…

Is that in dry air or damp?

The point being that lb is a unit of mass (hence the metric equivalent to inlbs is kgm, which isn’t a terribly useful unit for anything I can think of)? Or is there some other point I’m missing here?

CountZero – Member

Is that in dry air or damp?

an excellent question, you are on your way to understanding measurement uncertainty.

want a job? (a half serious question…)

you are on your way to understanding measurement uncertainty.

But how far along are you on the way to measuring the point you are at on your journey towards understanding the uncertainty of measurement?

The simple answer is we just don’t know. But its safe to say you probably won’t get there before teatime.