How to Convert Knots to Feet per second (kn 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 knots into feet per second by hand, with examples and a quick-reference table.
The conversion
To convert knots to feet per second, multiply the value by 1.687808399. To go the other way, divide by the same number (or multiply by 0.5924843132). For a quick estimate, multiply by about 1.7.
Feet per second = knots × 1.687808399
Worked examples
- 3 kn = 5.0634 ft/s
- 12.5 kn = 21.0976 ft/s
- 75 kn = 126.5856 ft/s
Knots to Feet per second 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 |
| 20 kn | 33.7562 ft/s |
| 25 kn | 42.1952 ft/s |
| 50 kn | 84.3904 ft/s |
| 100 kn | 168.7808 ft/s |
| 250 kn | 421.9521 ft/s |
| 500 kn | 843.9042 ft/s |
| 1,000 kn | 1,687.81 ft/s |
Common questions
Is kn 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 Knots converter.
Mistakes to avoid
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.
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.
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Background
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
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.
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 Knots to Feet per second Converter or browse all speed converters.
Run your own numbers: Knots to Feet per second Converter