How to Convert Miles per hour to Feet per second (mph to ft/s)
Speed conversions come up with expressway limits in km/h, foreign car specs in mph and wind speeds reported in knots by the Meteorological Service. This guide shows how to convert miles per hour into feet per second by hand, with examples and a quick-reference table.
The conversion
To convert miles per hour to feet per second, multiply the value by 1.4666666667. To go the other way, divide by the same number (or multiply by 0.6818181818). For a quick estimate, multiply by about 1.5.
Feet per second = miles per hour × 1.4666666667
Worked examples
- 3 mph = 4.4 ft/s
- 12.5 mph = 18.3333 ft/s
- 75 mph = 110 ft/s
Miles per hour to Feet per second table
| Miles per hour | Feet per second |
|---|---|
| 1 mph | 1.4667 ft/s |
| 2 mph | 2.9333 ft/s |
| 5 mph | 7.3333 ft/s |
| 10 mph | 14.6667 ft/s |
| 20 mph | 29.3333 ft/s |
| 25 mph | 36.6667 ft/s |
| 50 mph | 73.3333 ft/s |
| 100 mph | 146.6667 ft/s |
| 250 mph | 366.6667 ft/s |
| 500 mph | 733.3333 ft/s |
| 1,000 mph | 1,466.67 ft/s |
Common questions
Is mph to ft/s exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Feet per second to Miles per hour converter.
Mistakes to avoid
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Forgetting squared and cubed units
Area and volume factors are the length factor squared or cubed, so 1 m² is about 10.76 sq ft, not 3.28.
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Background
A conversion table is handy for common values, but a calculator is faster and avoids interpolation errors for anything in between.
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
Unit conversion is simply multiplication by a fixed ratio. The ratio between two units of the same quantity never changes, so once you know it you can convert any value in either direction.
For any value, use the Miles per hour to Feet per second Converter or browse all speed converters.
Run your own numbers: Miles per hour to Feet per second Converter