Basically people using numbers as symbols. Quite annoying.
> Lumber's nominal dimensions are larger than the actual standard dimensions of finished lumber. Historically, the nominal dimensions were the size of the green (not dried), rough (unfinished) boards that eventually became smaller finished lumber through drying and planing (to smooth the wood). Today, the standards specify the final finished dimensions and the mill cuts the logs to whatever size it needs to achieve those final dimensions. Typically, that rough cut is smaller than the nominal dimensions because modern technology makes it possible and it uses the logs more efficiently. For example, a "2×4" board historically started out as a green, rough board actually 2 by 4 inches (51 mm × 102 mm). After drying and planing, it would be smaller, by a nonstandard amount. Today, a "2×4" board starts out as something smaller than 2 inches by 4 inches and not specified by standards, and after drying and planing is reliably 1½ by 3½ inches (38 mm × 89 mm).
https://en.wikipedia.org/wiki/Lumber#North_American_softwood...
Shoe sizes often measure the size of the last, not the foot. One shoe company I've bought from in the past had a warning on their webpage that they use different manufacturing processes for different models, so the same numbered size of two similar-looking shoes actually differ by quite a bit.
(Fortunately, e-stores selling shoes were bitten enough by the ridiculousness of that problem that they ended up providing scales translating shoe numbers to centimeters.)
Ultimately, the best workaround I've seen was the one the father of my SO used - he would measure the foot of his child, then cut a wooden stick to appropriate length, and go with that stick to the shoes store.
There is a bit of insanity in that women's and children's sizes are derived from that in more than one way.
There are two ways of determining size, but they are supposed to coincide, theoretically.
Manufacturers use the "last length" as the basis for shoe size. However, that is not the foot length, and how a shoe with a given "last length" fits a given foot is a variable and so the fit ultimately requires testing. The last length is supposed to be about two shoe sizes larger than the foot length.
The last length formula is L3 - 24. So a last length of 12 inches (one foot) corresponds to size 12. From there, surrounding sizes are 1/3 of an inch increments. Which is the odd thing: where else you do you see increments of 1/3 inch?
Thus, in any case, if you have a 12" foot, that's a US men's size 14.
The foot measuring instrument you see in stores, Brannock's Device, accounts for this and so its formula is L3 - 22.
So these sizing systems are intended to coincide, but are different estimators.
You can see that using centimeters doesn't solve all the problems. Suppose centimeters were used, but the manufacturers used last-length centimeters rather than foot centimeters. You'd have to convert your foot length to last length according to some rule of thumb, and then ultimately resolve things by trying the shoe. If manufacturers had to use foot centimeters, they wouldn't be able to measure some trivial property of the shoe like last size to determine size. Foot centimeters aren't absolute; they would have to use some representative model of a foot and base it off that: still no guarantee that a 27cm size based on a representative model foot fits your 27cm foot.
According to the L x 3 - 24 rule, these boot should be nearly an inch different (or at least, their lasts). Maybe the US system is theoretically simple, but in practice it seems to be just an arbitrary number that can't be meaningfully compared to anything except the same model of shoe from the same company.
In contrast, I've ordered shoes from Japan 3 times, from 3 different companies, and I did it by putting a ruler next to my foot, and then choosing that number of centimeters in the online form. Every time, I got a shoe that fits great.
Maybe using an absolute length doesn't solve all problems, but my experience (with sample size of probably N<20) is that it works far better in practice. An arbitrary unit of measurement removes accountability, by way of obfuscation, and gains us nothing.
I'm not fully convinced by the argument that manufacturers (or at least distributors) can't use foot centimeters - after all, somehow I can successfully buy shoes on-line by measuring my foot and then using vendor-provided foot-length-to-shoe-size conversion scale to pick appropriate size. From the experience of myself and everyone else I asked around, this works reliably.
A foot long flat bread is actually longer than 12in.
Read that somewhere.