Feet Per Second to Mach (ft/s to Ma)

1 foot per second equals 0.0008956960746 Mach (rounded).

How to convert feet per second to Mach

To convert feet per second to Mach, multiply the number of feet per second by 0.0008956960746. The factor is rounded to 10 significant digits. To go the other way, multiply Mach by 1,116.450131 (rounded).

Mach = feet per second × 0.0008956960746

Example: 10 feet per second = 0.008956960746 Mach.

Approximate value. Standards for the Mach varied by place and period, so this converter uses the most commonly cited value. Treat results as estimates, not exact figures.

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

Mach (Ma)

ScientificCurrent unitApproximate value

The speed of sound at sea level in standard conditions (15 °C): about 340.294 m/s or 1,225 km/h. The speed of sound varies with temperature and altitude.

Ernst Mach, the Austrian physicist and philosopher born in Moravia in 1838, never defined a unit of speed, yet the ratio carries his name. In 1887 he and Peter Salcher presented a paper on photographing processes in air caused by projectiles, including a shadowgraph of the bow shock around a supersonic bullet fired from a Werndl carbine. The ratio of flow speed to the local speed of sound was later named for him.

Mach is therefore a dimensionless number, not a fixed speed, and because the speed of sound depends on temperature, so does Mach 1. It is about 340 m/s (1,225 km/h) in dry air at 15 °C at sea level, 343 m/s at 20 °C, and about 295 m/s above 11 kilometers where the air is cold. Flight is called subsonic below 0.8, transonic from 0.8 to 1.2, supersonic from 1.2 to 5 and hypersonic from 5 to 10. On 14 October 1947 Chuck Yeager flew the Bell X-1 to Mach 1.06, reported as 361 m/s.

1 Mach = 340.294 meters per second (approximately).

Sources: Wikipedia: Mach number; Wikipedia: Ernst Mach; Wikipedia: Speed of sound

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