Feet Per Second to Miles Per Hour (ft/s to mph)

1 foot per second equals 0.6818181818 miles per hour (rounded).

1 foot per second = 0.6818181818 miles per hour

How to convert feet per second to miles per hour

To convert feet per second to miles per hour, multiply the number of feet per second by 0.6818181818. The factor is rounded to 10 significant digits. To go the other way, multiply miles per hour by 1.466666667 (rounded).

miles per hour = feet per second × 0.6818181818

Example: 10 feet per second = 6.818181818 miles per hour.

About these units

Foot Per Second (ft/s)

US & ImperialCurrent unit

Exactly 0.3048 m/s. Used for velocity in US engineering, ballistics and fluid flow.

Compound units rarely have a recorded inventor, and the foot per second is a plain example: it is just a foot divided by a second. The foot underneath it began as a body-based length ranging historically from about 250 to 335 millimeters, with ancient Greek and Roman feet near 300 mm. Before the SI arrived in 1960, feet per second, miles per hour and knots were more common than meters per second, depending on region.

The 1959 international agreement fixed the foot at exactly 0.3048 meter, so one foot per second is exactly 0.3048 m/s, about 1.097 km/h or 0.6818 mph. Sound moves at about 1,125 ft/s in dry air at 20 °C, which is 343 m/s. Chuck Yeager's Bell X-1 reached about 361 m/s in 1947, near 1,184 ft/s. The unit remains common in American engineering and science, where lengths are still given in feet and inches.

1 foot per second = 0.3048 meters per second (exactly).

Sources: Wikipedia: Foot per second; Wikipedia: Foot (unit); NIST Guide to the SI, Appendix B.8: conversion factors

Mile Per Hour (mph)

US & ImperialCurrent unit

Exactly 0.44704 m/s. The unit for road speeds in the US, UK and a few other countries.

Early British motoring law is the best window into this unit. The 1861 Locomotive Act set a limit of 10 mph for light locomotives. The 1865 Red Flag Act cut it to 4 mph in the country and 2 mph in towns, with a person walking ahead with a flag. The Locomotives on Highways Act of 1896 raised it to 14 mph, and the Motor Car Act of 1903 to 20 mph. In 1931 all limits for cars were abolished, and 30 mph in built-up areas returned in 1935.

The mile per hour combines the mile, set at 5,280 feet in Elizabeth I's reign, with the hour, and it equals exactly 0.44704 m/s or 1.609344 km/h. The United Kingdom and United States use it on roads, along with several smaller countries, mostly territories or former territories of those two, and the US, Canada and Ireland use it for rail. Sports such as cricket, tennis and baseball quote ball speeds in it. Aviation and shipping prefer knots, about 0.869 of one mph each.

1 mile per hour = 0.44704 meters per second (exactly).

Sources: Wikipedia: Miles per hour; Wikipedia: Speed limits in the United Kingdom; Wikipedia: Mile

Related conversions

See all speed units.