How many km per hour can a human swim?

Answer 1

Speed of a swimmerA strong swimmer can swim upwards of 2 to 3 km in an hour. However, at a dead sprint, one can swim at about 10 km/h, with the human record probably somewhere around 14 to 15 km/h.

World-class swimmers can swim approximately 5 km in an hour in open water without currents. They almost maintain this speed over a 25-km course. The usual result for 25 km is around 5 hours and 15 minutes. In an open-water swim down the river, the speed can easily reach 10 km/h (for example, 88 km in Parana river in 8 hours, 46 minutes).

The top speed of the world's best sprinters is around 2.2 m/s or 8 km/h. This is pure swimming speed. The best performances in the 25-m and 50-m freestyle events indicate slightly better average speed, but this may be due to starting jumps and flip turns.

A simple formula for the max speed for a non planning boat is v=k sqrt(LWL) where k= constant =1,25, LWL=length at waterline in meters and v=velocity in m/s. A 2 m long swimmer thus has an approximate upper limit of 1,25 * sqrt(2) or about 6 m/s. Obviously it gets harder the closer to the limit velocity.