Miles per Hour to Feet per Second
Convert miles per hour (mph) to feet per second (ft/s). Both measure velocity, and the conversion comes up in driving, aviation, sports work.
The Formula
``
feet per second = miles per hour × 1.46666666667
miles per hour = feet per second × 0.681818181818
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One miles per hour is 1.4667 feet per second, and one feet per second is 0.681818 miles per hour.
Conversion 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 |
| 25 mph | 36.6667 ft/s |
| 50 mph | 73.3333 ft/s |
| 100 mph | 146.6667 ft/s |
| 500 mph | 733.3333 ft/s |
| 1,000 mph | 1,466.67 ft/s |
The Other Direction
| 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 |
| 25 ft/s | 17.0455 mph |
| 50 ft/s | 34.0909 mph |
| 100 ft/s | 68.1818 mph |
| 500 ft/s | 340.9091 mph |
| 1,000 ft/s | 681.8182 mph |
What Each Unit Is
Miles per Hour (mph) — miles travelled per hour, equal to 1.609344 km/h exactly. The road-speed unit of the US and UK.
Feet per Second (ft/s) — feet travelled per second, equal to 0.3048 m/s exactly. Used in US ballistics, fluid dynamics and some aviation contexts.
A Sense of Scale
Residential limits are 25–30 mph- US freeways are 65–75 mph
- A jog is 6 mph
- A pitched baseball leaves the hand near 130 ft/s
- Walking is about 4.6 ft/s
Precision
The factor 1.46666666667 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.
In Code
`javascript
const milePerHourToFootPerSecond = (value) => value * 1.46666666667;
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Where This Conversion Comes Up
- Driving
- Aviation
- Sports
- Shipping
- Weather
How Many Decimals Do You Need?
Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 mph with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 mph becomes | Error |
|---|---|---|---|
| 0 | 1 | 137 | 31.8182% |
| 1 | 1.5 | 205.5 | 2.2727% |
| 2 | 1.47 | 201.39 | 0.2273% |
| 3 | 1.467 | 200.979 | 0.0227% |
| 4 | 1.4667 | 200.938 | 0.0023% |
The right number of significant figures is set by your input, not by the converter. If you measured miles per hour to three significant figures, the answer in feet per second is only good to three — writing more digits claims precision the measurement never had.