The decimeter is certainly an overlooked unit, and it’s a shame it’s relegated to relative obscurity - I use it occasionally even if people give me weird looks. Ideally I think something in the range of 20-30cm would make for a nice base unit - about the length of a forearm. Deci-units around the length of a finger segment, and centi-units being a slightly larger millimetre-equivalent. A deca-unit would be about the height of a doorframe.

Don’t misunderstand me, imperial sucks. I just wish the metric system had defined the metre to be smaller, that’s all.

See my other comments in this thread. I think most people would prefer if the common measurements they made with common units landed in the number range of about 0.2-10-ish. The human brain is good at visually estimating small groups so any unit system should try to lean into that and put the scale of commonly measured values in that range. Obviously as things get bigger you end up with tens or hundreds of units which start to lose semantic meaning, especially for quick estimations or relative comparisons, so you should start thinking of switching units at this point. Likewise when values get below about 0.1 they get hard to visualise, so most people switch units here.

My point being - I think the base unit of one metre is too large for most daily tasks - most things that are around a human scale end up being less than one metre, and I think the centimetre is too small - most things on the human scale end up being dozens of centimetres at least. Both fall outside that ideal range of ‘a small handful’ which the brain is good intuitively and subconsciously working with.

You’re right, I have no interest in sports. Though in that case under this modified metric a decametre would be approximately on the same scale as the previous metre.

Don’t get me wrong, imperial sucks, but the scale of the typical measurements with typical units lands nicely in what the human brain is good at visualising - small groups of up to about 10 (see my comments to other people in this thread). I think most people would prefer when the common measurements they make with common units end up in the range of 0.2 to 10-ish. Centimetres are too small for that and you measure using dozens or hundreds of them, which starts to lose semantic meaning, which makes visual estimation a bit trickier, especially with comparative distances. You start thinking in terms of tens or hundreds of cm visually to keep it under control which is just another layer of cognitive load. I think the perfect unit system would avoid this as much as practical. The existing metric metre is fine for outdoor activities, but I would argue most people aren’t out measuring fields all day, they’re looking at things on the same scale as their own body for the most part. Metres are a bit big for that.

True, I converted metric to imperial with minimal rounding, as I didn’t want to give either an unfair advantage. You could round up again to 5-6.2 or down for 4.8-6.2 but my point stands. I think most people would prefer if the units they used most often were in the range of 0.2-10-ish. I don’t think that’s unreasonable.

You can memorise that a person is 10 billion nanoangstroms tall if you like, but surely you can’t be saying that it’s more convenient than using a scale that’s the same order of magnitude as the thing itself. That’s why we use the metric system after all, to give many units as close to the scale of what we’re trying to measure as possible in a standardised way.

No, I’m not. I live in a commonwealth country that transitioned to metric well before I was born. Recently I’ve had to work with American companies as part of my job.

Don’t get me wrong, the imperial system is horrible, I just wish the metric system had a unit closer in length to feet or inches. Yards would be an annoying unit for human-scale measurements too. Even the name implies it’s usage - it’s for measuring (small) areas of land, which are usually much bigger than humans after all. That’s not a problem in imperial though since no-one would say ‘my pen is 0.1 yards long’, they’d measure in inches instead because it comes out as a nice, human brain-friendly small number like 4 or 6.

All measurements are arbitrary

Perhaps in a perfectly rational world, but humans are silly creatures. The human brain evolved to deal with small numbers. Distinguishing one vs two lions is important, but distinguishing 14 vs 15 lions is not, so our brain immediately recognises numbers up to about six and has to rely on conscious counting for anything larger. If I told you that “This dog is two ducks tall” you’d have a pretty good idea of how big the dog is, but if I said it was “20 mice tall” you might have trouble visualising, or worse “450 ants tall” at which point I would have no idea. Our brains don’t innately have the ability to accurately conceptualise large numbers, which is why the metric prefix system works so well - it keeps numbers relatively small. I think the same logic applies to decimals and fractions. Simple fractions like halves through to perhaps fifths can be visually conceptualised at a glance, but beyond that it requires calculation.

What that means to me is that ideally your measurement unit should be big enough to be able to measure most things you deal with on a daily basis using no more than say 10 units (arbitrary, I could be persuaded down to 6 or up to 20), and still measuring most things without going smaller than about 0.2 units. As an example, consider human height (after all, what could be more a more human measurement?). The average person is between 1.5 and 1.9m tall, which is not a great start since we’re riding close to the 0.2 ‘lower resolution’ just describing the whole range. You could use centimetres but then you’re looking at 150 or 190 which is much too large to visualise nicely. Decimetres is better but not great. Feet is a pretty good fit for this, since that’d be about 4.9 to 6.2 ft. We haven’t violated either the max or minimum requirements and we still have a decent resolution within the range too.

having easy conversions is much more useful than a “natural” base unit.

I agree, but my whole point is that we didn’t have to choose!

Because I have had to work with American companies as part of my job for the past couple years. For the entirety of my personal life and the rest of my professional life I use metric. I’ll grant you I should have said ‘almost exclusively’ in my previous comment, but I think that’s just splitting hairs.

That’s not the point I’m trying to make. You can derive a length from any number of physical constants to make it reproducible, but considering the divisor of exactly ten million suggests the metric committee were far more interested in making something ‘clean’ than something human-friendly. They could have basically done what they do with the modern redefinitions of the metre - the distance travelled by light in 1/299792458 ths of a second. Obviously they chose that number to keep the definition in line with the original, but they could have done that with the original definition to make the metre basically any length they wanted, but they didn’t.

Nice try! I live in a metric country and use exclusively metric units.

The metric prefix system is a fantastic invention, akin to the arabic number system. Honestly it’s surprising no one came up with it sooner… but (and I’m sure I’ll catch some flak for this) the metre is an awkward length - it’s too big for human scale measurements. The decimetre is not as bad but still not very good, and it’s also not commonly used. The centimetre has the opposite problem - it’s too small for the human scale but too big for precision work.

Don’t get me wrong, the horrible conversions between imperial units make the system unusable for me, but the unit lengths themselves are scaled to humans because they weren’t initially defined arbitrarily by some committee (why should the distance from the pole to the equator be used as the baseline for a measurement used by humans?). I think the inch and foot are great lengths to use on a daily basis, they feel quite natural.

What annoys me the most is that we could have had the best of both, since the foot and inch are only a factor of 12 apart, so we could have had a metre measuring about one foot and a decimetre measuring about an inch.