[psadauskas]

I read a study many years ago, I haven't been able to find it for awhile. It took people who had grown up using each system, and asked them to estimate things just by guessing. For example, "How long is that wall?" or "How far is it from here to the post office?" or "How heavy is this paperweight?". People who'd grown up using customary were significantly more accurate in their guesses.

The study surmised it was because those units had been developed over millennia to be useful at human scales. When eyeballing the length of a wall, centimeters are too granular and meters are to course, but feet are "just right". You might guess a wall is 12 feet long, and be pretty close, but 3 or 4 meters aren't that accurate, and nobody really guesses 3.5 meters.

Same with temperature. 0 - 100°F is about all we as humans will usually experience, so its very convenient when talking about the weather or HVAC thermostats.

They are worse when doing math or conversions, and while that's annoying for scientists and engineers, in most people's everyday lives it comes up so infrequently it doesn't really matter. If something is less than a mile, you don't suddenly convert to feet and do math, you just say "about a half mile".

Personally, I do woodworking (which in the US is always imperial) and 3d-printing (which is always metric), and often combine the two. When doing woodworking or carpentry, its nice that a foot is evenly divisible by 3 or 6, or that half of 3/8ths of an inch is 3/16ths.

[asdff]

It makes sense. Curling my finger it is pretty much dead on 1 inch from the tip to the first joint. My foot is a little shorter than 1 foot, but in shoes, pacing it out one foot after another, it is nearly dead on as well. A lot of people measure using anatomy with conventional units.

[johnea]

That sounds like total bullshit to me...