How to Convert Feet per second to Miles per hour (ft/s to mph)
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 feet per second into miles per hour by hand, with examples and a quick-reference table.
The conversion
To convert feet per second to miles per hour, multiply the value by 0.6818181818. To go the other way, divide by the same number (or multiply by 1.4666666667). For a quick estimate, multiply by about 0.68.
Miles per hour = feet per second × 0.6818181818
Worked examples
- 3 ft/s = 2.0455 mph
- 12.5 ft/s = 8.5227 mph
- 75 ft/s = 51.1364 mph
Feet per second to Miles per hour table
| Feet per second | Miles per hour |
|---|---|
| 1 ft/s | 0.681818 mph |
| 2 ft/s | 1.3636 mph |
| 5 ft/s | 3.4091 mph |
| 10 ft/s | 6.8182 mph |
| 20 ft/s | 13.6364 mph |
| 25 ft/s | 17.0455 mph |
| 50 ft/s | 34.0909 mph |
| 100 ft/s | 68.1818 mph |
| 250 ft/s | 170.4545 mph |
| 500 ft/s | 340.9091 mph |
| 1,000 ft/s | 681.8182 mph |
Common questions
Is ft/s to mph 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 Miles per hour to Feet per second converter.
Mistakes to avoid
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
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.
Background
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.
A conversion table is handy for common values, but a calculator is faster and avoids interpolation errors for anything in between.
Singapore adopted the metric system in the 1970s, replacing imperial units and traditional Chinese measures in most official uses. Metric units are now standard in schools, trade and government, but older units survive in property, markets and imported goods.
For any value, use the Feet per second to Miles per hour Converter or browse all speed converters.
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