Knots to Feet per Second
Convert knots (kn) to feet per second (ft/s). Both measure velocity, and the conversion comes up in driving, aviation, sports work.
The Formula
``
feet per second = knots × 1.6878098571
knots = feet per second × 0.592483801296
`
One knot is 1.6878 feet per second, and one feet per second is 0.592484 knots.
Conversion Table
| Knots | Feet per Second |
|---|---|
| 1 kn | 1.6878 ft/s |
| 2 kn | 3.3756 ft/s |
| 5 kn | 8.439 ft/s |
| 10 kn | 16.8781 ft/s |
| 25 kn | 42.1952 ft/s |
| 50 kn | 84.3905 ft/s |
| 100 kn | 168.781 ft/s |
| 500 kn | 843.9049 ft/s |
| 1,000 kn | 1,687.81 ft/s |
The Other Direction
| Feet per Second | Knots |
|---|---|
| 1 ft/s | 0.592484 kn |
| 2 ft/s | 1.185 kn |
| 5 ft/s | 2.9624 kn |
| 10 ft/s | 5.9248 kn |
| 25 ft/s | 14.8121 kn |
| 50 ft/s | 29.6242 kn |
| 100 ft/s | 59.2484 kn |
| 500 ft/s | 296.2419 kn |
| 1,000 ft/s | 592.4838 kn |
What Each Unit Is
Knots (kn) — one nautical mile per hour, or exactly 1.852 km/h. From the knots in a line paid out behind a ship: sailors counted knots passing in a fixed time to read speed.
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
An airliner cruises at 450–500 knots- A hurricane starts at 64 knots
- A pitched baseball leaves the hand near 130 ft/s
- Walking is about 4.6 ft/s
Doing It in Your Head
Multiply by 5, then divide by 3. That is off by 1.25% — close enough to judge a
distance, a weight or a price, and not close enough to sign off on a drawing.
Exact Mental shortcut 16.8781 ft/s 16.6667 ft/s 168.781 ft/s 166.6667 ft/s
Precision
The factor 1.6878098571 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.
Watch Out For
- Never say "knots per hour" — the "per hour" is already in the unit.
In Code
`javascript
const knotToFootPerSecond = (value) => value * 1.6878098571;
``
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 kn with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 kn becomes | Error |
|---|---|---|---|
| 0 | 2 | 274 | 18.4968% |
| 1 | 1.7 | 232.9 | 0.7222% |
| 2 | 1.69 | 231.53 | 0.1298% |
| 3 | 1.688 | 231.256 | 0.0113% |
| 4 | 1.6878 | 231.229 | 0.0006% |
The right number of significant figures is set by your input, not by the converter. If you measured knots to three significant figures, the answer in feet per second is only good to three — writing more digits claims precision the measurement never had.