The Size of Horses

You may not have given much thought to the size of the steed King Arthur sat on during the Middle Ages, but my brother has researched the matter. 

By definition a horse must be at least 57 inches tall or 14 hands and one finger. You are measuring, of course, the height of its withers. (I don't know who makes up the rules.)

You can estimate the height your colt will reach when the colt is six months old. The length of the colt's lower leg from hoof to knee is 93% of the size the lower leg will be when mature. The next step is too complicated to explain here, but if you set out to buy a horse to ride, pick one that weighs at least seven times what you do.  

A study of human skeletons indicates that men actually lost height in the Middle Ages, maybe two and a half fingers on average. But knights, while contemptibly short, were famously prodigious eaters. Most would have needed horses weighing close to 3,000 pounds. And a study of skeletal remains tells us they rode what we now call ponies. 

By some estimates, instead of weighing a seventh of their steeds, knights may have weighed about a quarter of the ponies they staggered in on. Keep in mind that the ideal knight was supposed to be broad-shouldered and narrow waisted, an effect mostly achieved with corsets and heavy metal armor, which cost many knights their lives, as they rode into battle unable to dismount or raise their arms above their waists.