How Much Does a Racehorse Weigh?

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The average thoroughbred racehorse weighs around 1036 to 1135 pounds. The average weight of a mature thoroughbred is 1256 pounds. These horses are raced at very young ages, usually beginning at around 2 years of age. Thoroughbreds are not physically mature until 5 years of age, at which point most have been retired from racing.