Feet per Second Calculator

International speed converter

Convert feet per second and miles per hour

Convert feet per second to miles per hour or reverse it with the exact 15-to-22 speed ratio for international units.

Result

1 ft/s = 0.681818 mph

Reference relationship22 ft/s = 15 mph exactly

Formula usedmiles per hour = feet per second × 15/22

Unit relationship

22 ft/s = 15 mph exactly

International feet per secondA speed of one international foot traveled each second.

International miles per hourA speed of one international statute mile traveled each hour.

A statute mile contains exactly 5,280 international feet and an hour contains 3,600 seconds, reducing the ratio to 15/22.

Worked example

Convert 88 ft/s to mph

1
Start with the international foot per second value
Use 88 ft/s.
2
Apply the exact relationship
Multiply the ft/s value by 15/22.
3
Write the international mile per hour unit
88 ft/s = 60 mph.

Quick reference

International feet per second to International miles per hour conversion table

Common ft/s values converted to mph
International feet per second (ft/s)	International miles per hour (mph)
1 ft/s	0.681818181818 mph
5 ft/s	3.40909090909 mph
10 ft/s	6.81818181818 mph
22 ft/s	15 mph
44 ft/s	30 mph
88 ft/s	60 mph
100 ft/s	68.1818181818 mph
220 ft/s	150 mph

Speed-unit derivation

Feet per second to mph, derived from the units

Feet per second and miles per hour express the same speed with different length and time units; their exact 15-to-22 ratio can be derived rather than memorized.

Step-by-step guide · Speed-unit derivation

Use exact anchor speeds to inspect a result

Exact distance: 1 mi = 5,280 ft
Exact time: 1 h = 3,600 s
Reference speed: 88 ft/s = 60 mph

Twenty-two feet per second
Multiplying 22 by 15/22 cancels the denominator, giving exactly 15 mph. A result near 32 mph would signal that the reverse factor was probably used.
Eighty-eight feet per second
The exact conversion is 60 mph. This is a convenient road-speed-sized benchmark even when the original ft/s reading came from a machine, projectile, or short test interval.
Fifteen miles per hour in reverse
Multiplying 15 mph by 22/15 returns exactly 22 ft/s, providing a round-trip check that does not depend on decimal approximations.

Feet per second to mph, derived from the units: Two reference points make direction mistakes easy to spot without replacing the full calculation.

Derive the 15/22 factor from distance and time

A speed conversion must change both the length unit and the time unit. The international statute mile contains exactly 5,280 international feet, while one hour contains exactly 3,600 seconds. Multiplying a feet-per-second value by 3,600 changes the time basis to an hour; dividing by 5,280 changes the distance basis to miles. The combined fraction 3,600/5,280 reduces to 15/22.

That derivation gives mph = ft/s × 15/22 and the reverse formula ft/s = mph × 22/15. No test-track observation or vehicle assumption is hidden in the factor. It is a consequence of the definitions of the units, so a precise implementation can carry the ratio through the calculation and round only the final display.

Use exact anchor speeds to inspect a result

Two reference points make direction mistakes easy to spot without replacing the full calculation.

Twenty-two feet per second
Multiplying 22 by 15/22 cancels the denominator, giving exactly 15 mph. A result near 32 mph would signal that the reverse factor was probably used.
Eighty-eight feet per second
The exact conversion is 60 mph. This is a convenient road-speed-sized benchmark even when the original ft/s reading came from a machine, projectile, or short test interval.
Fifteen miles per hour in reverse
Multiplying 15 mph by 22/15 returns exactly 22 ft/s, providing a round-trip check that does not depend on decimal approximations.

Do not manufacture speed from a distance alone

This page converts a speed that is already known. A trip length by itself has no speed until an elapsed time is supplied. Use the distance calculator when the unknown is route separation, or the pace calculator when distance and elapsed time need to be combined for running or walking analysis.

Pure length conversions should also stay separate. The kilometers to miles calculator changes a road or course distance without implying how fast it was covered, while the meters to feet calculator changes a linear measurement without introducing seconds or hours. Choosing by quantity prevents a plausible-looking dimensional error.

Resolve the ambiguous abbreviation fps

In motion and media discussions, the same three letters are often used for unrelated concepts.

ft/s is physical speed

It describes a length traveled during each second and can therefore be converted to mph, m/s, or another speed unit.

frames per second is a sampling rate

It counts images displayed or captured each second. Without an independent distance per frame, it contains no length and cannot be converted to miles per hour.

Context remains part of the input

Write ft/s rather than fps in technical notes when physical speed is intended. A clear unit symbol is as important as the numeric value because it preserves the dimension being converted.

Important limitations

This is a scalar speed conversion. It does not calculate acceleration, direction, aerodynamic effects, projectile trajectories, Mach number, measurement error, or condition-dependent velocity.

Review the stated scope, calculation method, assumptions, supported inputs, and effective dates, and obtain qualified advice before using a high-stakes result.

This formula passed its registered engineering tests and is published under an explicit site-owner policy authorization. No independent expert, QA, editorial, legal, or third-party review is claimed. Verify consequential results with a qualified professional.

Speed-unit derivation

Feet per second to mph, derived from the units

Feet per second and miles per hour express the same speed with different length and time units; their exact 15-to-22 ratio can be derived rather than memorized.

Step-by-step guide · Speed-unit derivation

Use exact anchor speeds to inspect a result

Exact distance: 1 mi = 5,280 ft
Exact time: 1 h = 3,600 s
Reference speed: 88 ft/s = 60 mph

Twenty-two feet per second
Multiplying 22 by 15/22 cancels the denominator, giving exactly 15 mph. A result near 32 mph would signal that the reverse factor was probably used.
Eighty-eight feet per second
The exact conversion is 60 mph. This is a convenient road-speed-sized benchmark even when the original ft/s reading came from a machine, projectile, or short test interval.
Fifteen miles per hour in reverse
Multiplying 15 mph by 22/15 returns exactly 22 ft/s, providing a round-trip check that does not depend on decimal approximations.

Feet per second to mph, derived from the units: Two reference points make direction mistakes easy to spot without replacing the full calculation.

Derive the 15/22 factor from distance and time

Use exact anchor speeds to inspect a result

Two reference points make direction mistakes easy to spot without replacing the full calculation.

Twenty-two feet per second
Multiplying 22 by 15/22 cancels the denominator, giving exactly 15 mph. A result near 32 mph would signal that the reverse factor was probably used.
Eighty-eight feet per second
The exact conversion is 60 mph. This is a convenient road-speed-sized benchmark even when the original ft/s reading came from a machine, projectile, or short test interval.
Fifteen miles per hour in reverse
Multiplying 15 mph by 22/15 returns exactly 22 ft/s, providing a round-trip check that does not depend on decimal approximations.

Do not manufacture speed from a distance alone

Resolve the ambiguous abbreviation fps

In motion and media discussions, the same three letters are often used for unrelated concepts.

ft/s is physical speed

It describes a length traveled during each second and can therefore be converted to mph, m/s, or another speed unit.

frames per second is a sampling rate

It counts images displayed or captured each second. Without an independent distance per frame, it contains no length and cannot be converted to miles per hour.

Context remains part of the input

Write ft/s rather than fps in technical notes when physical speed is intended. A clear unit symbol is as important as the numeric value because it preserves the dimension being converted.

22 ft/s = 15 mph exactly

Convert 88 ft/s to mph

International feet per second to International miles per hour conversion table

Twenty-two feet per second

Eighty-eight feet per second

Fifteen miles per hour in reverse

Derive the 15/22 factor from distance and time

Use exact anchor speeds to inspect a result

Do not manufacture speed from a distance alone

Resolve the ambiguous abbreviation fps

ft/s is physical speed

frames per second is a sampling rate

Context remains part of the input

Important limitations

22 ft/s = 15 mph exactly

Convert 88 ft/s to mph

International feet per second to International miles per hour conversion table

Twenty-two feet per second

Eighty-eight feet per second

Fifteen miles per hour in reverse

Derive the 15/22 factor from distance and time

Use exact anchor speeds to inspect a result

Do not manufacture speed from a distance alone

Resolve the ambiguous abbreviation fps

ft/s is physical speed

frames per second is a sampling rate

Context remains part of the input