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Comment by MarcScott | Hacker News Reader

It's no more complicated than measurements and weights in the imperial system.

We're a weird country. We decimalised our currency, our weights and measures in shops and science, but we can't let go of imperial measures. Amongst the general population, people are far more comfortable talking about miles and miles per hour, than kilometers. Land sizes are still measured in acres and hectares. If you ask anyone their height, you'll probably get an answer in feet and inches, but ask their weight and they're more likely to tell you in kilograms rather than pounds and stone.

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Some years ago I was a carpenter in the UK. From what I can see this has changed little since then... If I were laying out for sheet materials...mdf or plasterboard came in metric sizes 2400x1200mm so joists or studs went at 400mm centres. If I were laying out for plywood it came in 8x4ft sheets so I would use 16 inch centres.

If I were measuring a space to cut something to fit I would use inches or feet and inches, 23 an 1/8, for instance.

I might need a small hole about 1/8 of an inch, open my drill box and select a 3mm.

If I were ordering timber I might ask for a 3 metre length of 4x2. As in 4x2 inches! If 3m were too long you might prefer an 8ft length. The yardman would walk you straight to the 2.4m pile without hesitation. Of course timber lengths are in 300mm increments to align with the feet of old. When you got your despatch note it would say something like 2400x100x50. Or perhaps they used regularised timber and it would have been machined down to 97×47 which may or may not be mentioned on the ticket. It would still be called 4x2 whatever!

Thing is, none of this caused us any trouble whatsoever. Well.. apprentices who learnt cm at school (which was NEVER used in construction) had a fun few weeks at the beginning.

I had engineers use all the same terms to me verbally, but never in their written work which were always in mm

A lot of those things are not actively measured but are more experiential or used as an approximation. Height in feet is about how tall someone is, not their exact height. A mile to the pub is about how long it will take to walk, not the exact distance. Younger Brits will tend to use these terms in conversation but revert to metric more when something actually needs to be measured.

> A mile to the pub is about how long it will take to walk, not the exact distance. Younger Brits will tend to use these terms in conversation but revert to metric more when something actually needs to be measured.

Doesn't this get confusing when all traffic and road signs, car instruments, etc. are in miles and miles per hour?

Don't even think about fuel efficiency ratings (MPG) vs. petrol dispense volume (L).

You don't typically need to reason about those numbers though. You know what 30mph feels like.

I don't recognize the 'vibiness' of imperial length and distance measurements at all. Perhaps this is a pareidolic interpretation which came to you when you noticed people using both sets of measurement types?

I can’t remember when I last heard a Brit of any age use kilometres in any context.

I assume that, as in the US, SI units are used in many scientific and technical contexts.

It’s kilometres specifically that I hear used rarely in the Uk. Other SI units are relatively common I agree.

People who are into running/cycling use "K" a lot, personally I think it's because once someone starts talking in km, if you use miles your stats will look bad by comparison. I know trackers/apps probably had this as default from the start because Europe=metric but so did a lot of satnavs and it didn't change our language in the same way.

mm is used constantly in engineering and km will be used for long distances in professional settings.

Metres and mm I hear a lot but kilometres very little - mainly because of miles on road signs. I guess the last reference I remember is to 5K runs.

It's rare to need kilometres in engineering, but I know from a friend that works at Network Rail that everything is done in kilometres, except final conversions on many older railway lines where the mileposts still measure miles.

Those small blue signs at the side of motorways, and the white emergency location posts, both use kilometres.

>It's rare to need kilometres in engineering

Yeah, the thing with imperial units and engineering is that once you get anywhere near mass, weight, force, energy, and all the related units for same, it can get very confusing and error prone. So are we talking pounds-mass, pounds-force, or slugs? (The latter being something that probably no one who didn't take engineering/physics/etc. classes has ever heard of.)

It's incredibly common to use km here, and miles.

What's amazing is how we mix the two. Case in point, my wife and I are both runners, she measures her pace in minutes per mile, I use minutes per km. When we exchange stats we have to do the conversion. She does it as her running club uses the mile convention. This is despite the fact that we're doing 10 km races. So you're running a 10 km and talking about a '7 minute mile'?!

We're an eccentric bunch!

Hectares are metric, 1ha = 100m × 100m = 10000m².

Distances on road signs are still in miles and speed limits are still in mph, so familiarity with miles reflects their official status, not just British weirdness/quaintness.

And also, unlike the weirdness of pre-decimal currency or some of our more obscure weights and measures units, the miles we talk about are rough approximations that aren't supposed to be subdivided or converted into anything precise (or anything more precise than "about half a mile") so there's no particular advantage to using an SI unit

Disagree. A mile is a well-defined quantity, and furlongs are widely understood by older men.

I still find it easier to assess my body weight in stones and pounds (14 pounds, one stone). I'm currently about 13 stone 7lb. I have no idea what my weight is in kilos.

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