In my opinion horses come in two sizes: too small and big enough. I’m 6′ tall and have long legs. I’ve never measured the horses that I currently own because they take up my leg and they feel right, but I’d guess that one is 16.1 and the other is about 16.2. In the past, I has a horse that was only about 15.3, but even he never felt too small. Both of mine are big enough without venturing into the “supersized” horse that requires custom tack, special shoes, and which is vulnerable to a host of size related soundness issues.
I’m sometimes amazed by the sheer size of the horses that some people ride. I have a friend who owns a draft cross that looks like it stepped out of a Budweiser commercial. He’s easily more than 18 hands. He certainly would not look out of place at a medieval joust and could easily carry a knight in a full suit of armor.
Now my friend — like me — is close to 6′ tall. All the horses she’s owned have been large. A previous horse was 19 hands, and it boggled my mind to imagine what type of mounting block (or ladder) you would need simply to get on him. At least I can understand why she likes larger horses. At times I’ve gone to shows (usually dressage shows) and seen tiny women riding huge horses. My first reaction has always been, save those horses for those of us who actually need them!
Large horses are definitely in demand these days. I’ve heard plenty of moderately sized people state with great assurance that they would never buy a horse that stands less than 16.2 and that they prefer horses over 17 hands! In fact, sellers commiserate when they have horses a mere 15.2 as the market for them is so much smaller.
So how large a horse do you actually need? I came across an equation on the Internet that is supposed to help you calculate, although it’s more related to rider weight than height.
Add up the total weight of the horse, rider, and tack. Our example: Horse + rider + tack= 1188 pounds
Measure the circumference of the cannon bone midway between the knee and fetlock. Our example: 7.5 inches
Divide the total weight by the circumference. Our example: 1188 / 7.5 = 158.4
Divide the result by two. Our example: 158.4 / 2 = 79.2
Values below 75 are great! Values from 75-80 are acceptable. Values over 80 indicate weaker legs and a need to train carefully, especially downhill. At this level a rider needs a horse with more substance.
I’m not sure that I would bother with the calculation, although I believe it makes sense that a horse with more “bone” is capable of carrying more weight. In my experience, I’ve found that rather than height, it’s the build of the horse that makes the difference. A horse with a large barrel and well sprung ribs can take up your leg better than a taller, narrow built horse.
I prefer a horse that’s built with a reasonably long neck and a good sized shoulder — since my torso is long, it helps me balance better. Generally, I like a horse with a slightly long back for the same reason. However, those rules are made to be broken. My OTTB is quite short coupled and I have to be very careful to keep my upper body still as he is very sensitive to shifts in weight. He may not be very big or long, but I love the fact that he’s nimble as a cat and thinks he’s just a bigger horse than he measures.