Common abbreviation: HH. Note: HH can have two meanings. See Husband Horse.
This isn’t where one stands wildly waving one’s hands in the air yelling “But they stepped BACK!” or an old Clint Eastwood western you’ve seen a million times.
A ‘Hand’ is the universally agreed standard measurement of the height of the horse. (See Sticking Out). One hand equals 4 inches. So a horse that is 16HH is a horse that has 16 of those 4 inch measurement increments. See? Not complicated at all. A horse that is 16.2 is one that has 16 of those 4 inch measurement increments PLUS 2 inches. Got that? Wow, really? Why are you still reading this? I believe MIT is currently accepting applications. Go!
If you see an ad for a horse that is 16.6 HH run. That horse is really 17.2 (or 14.3 depending on how stupid the owner is with the measuring stick, clearly they don’t know what they’re doing.)
Still with us? No? A horse that is 16.2 HH is actually 5 feet 5 inches tall at the shoulder. Wow, what a lot of work, huh. Who knew you needed math skills and medieval English to measure a horse with a measuring stick? Why not make a normal measuring stick? Uh. I don’t know. We like you to stay confused? On that note, in a horse-for-sale ad, HH without a number in front of it can also mean: Husband Horse.