How fast can a horse run in mph?

Quarter horses that are bred specifically for running short distances can reach speeds of 50 mph, whereas thoroughbred horses, which are bred for running and not racing speed, can reach speeds of approximately 40 mph. Some horses are not bred for running at all, and they are only able to complete a running walk that can reach speeds of 15 mph, or a canter of approximately 30 mph.

The speed of each horse is dependent on the length of its stride, body build, genetics, athletic ability and health condition. Some horses are simply built to run faster than others.