Feet per second to Miles per hour Converter

How many mph is one foot per second?

One foot per second is 0.681818 miles per hour (the repeating decimal 0.6818...). Both units use the international foot and mile, and the link between them is exact: a mile is 5,280 feet and an hour is 3,600 seconds.

mph = fps × 3,600 ÷ 5,280 = fps × 15 ÷ 22The multiplier 15/22 is about 0.681818.

Multiplying by 3,600 turns "feet per second" into "feet per hour", and dividing by 5,280 turns feet into miles. Simplifying 3,600/5,280 by their common factor of 240 leaves the fraction 15/22.

Where feet per second shows up

Miles per hour is the everyday road and sport speed in the United States and the United Kingdom, while feet per second is the working unit wherever distances are short and times are measured in seconds. Typical places are ammunition and airgun packaging, where muzzle velocity is quoted in fps, physics and engineering problems in customary units, and wind or flow estimates over a few feet.

Because the two scales sit so far apart, an fps number can look very large next to the mph figure people expect. Converting makes the comparison meaningful.

How to convert fps to mph

1. Enter the speed in feet per second in the first box.
2. The second box shows miles per hour as soon as you type.
3. By hand, multiply the fps value by 15 and divide by 22.

Example 1. A car travelling at 44 ft/s: 44 × 15 ÷ 22 = 30 mph exactly.

Example 2. A thrown ball leaves the hand at 130 ft/s. 130 × 15 ÷ 22 ≈ 88.64 mph.

Example 3. A box of ammunition lists a muzzle velocity of 1,150 fps. 1,150 × 15 ÷ 22 ≈ 784.09 mph, a little above the speed of sound in air at 20 °C.

The speed of sound in air at 20 °C is close to 1,125 ft/s, or about 767 mph. Any speed above that figure is supersonic, so the 1,150 fps round in the example leaves the barrel just past that threshold.

fps to mph conversion table

A mental shortcut

Remember the pair 88 ft/s = 60 mph. Since 60 ÷ 88 is about 0.68, multiplying an fps value by 0.68 gets within a fraction of a percent. For a rougher estimate, take two thirds of the fps figure: 90 fps becomes about 60 mph, roughly 2% below the exact 61.36.

To convert in the opposite direction use the mph to fps converter. For other speed units, the speed converter handles several at once, and the speed calculator works out speed from distance and time.