Accepted wisdom in the horse world tells us that an “average” light horse weighs about 1,000 pounds, or 450 kg. A draft horse, upwards of double that. But does that rather arbitrary figure really mean anything? After all, what is an “average” horse? To a dressage competitor, it might be a 17-hand warmblood, while to a cutting horse enthusiast, it might be a 14-hand Quarter Horse or Arabian. In their own little universes, each might be said to be “average,” yet their weight difference might be more than 600 pounds!
The 1,000-pound estimate is good enough for many purposes; for deworming, for example, it’s a safe enough ballpark figure because modern deworming drugs are designed with huge margins of safety, making over-dosing a remote risk. (Under-dosing, on the other hand, can happen quite easily, and some researchers feel it might contribute to an incomplete worm kill and subsequent increased resistance by the remaining parasitic population in the gut…but that’s another article.) But for other situations–such as calculating the amount of feed your horse should eat each day–having a more accurate idea of his true weight is a definite asset.
Weighing your horse isn’t a simple matter. Even if you could teach him to stand with all four feet on your bathroom scale, chances are he’d exceed its maximum capacity and cause it to pop all of its springs. Nor are horse-sized scales readily available (they do exist, mostly in the setting of university veterinary hospitals).
You could, of course, use a set of public weight scales designed for measuring truck payloads; these can be found at some