How to Convert Miles per hour to Knots (mph to kn)
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 knots by hand, with examples and a quick-reference table.
The conversion
To convert miles per hour to knots, multiply the value by 0.8689769926. To go the other way, divide by the same number (or multiply by 1.1507784538). For a quick estimate, multiply by about 0.87.
Knots = miles per hour × 0.8689769926
Worked examples
- 3 mph = 2.6069 kn
- 12.5 mph = 10.8622 kn
- 75 mph = 65.1733 kn
Miles per hour to Knots table
| Miles per hour | Knots |
|---|---|
| 1 mph | 0.868977 kn |
| 2 mph | 1.738 kn |
| 5 mph | 4.3449 kn |
| 10 mph | 8.6898 kn |
| 20 mph | 17.3795 kn |
| 25 mph | 21.7244 kn |
| 50 mph | 43.4488 kn |
| 100 mph | 86.8977 kn |
| 250 mph | 217.2442 kn |
| 500 mph | 434.4885 kn |
| 1,000 mph | 868.977 kn |
Common questions
Is mph to kn 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 Knots to Miles per hour 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.
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Background
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.
A conversion table is handy for common values, but a calculator is faster and avoids interpolation errors for anything in between.
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.
For any value, use the Miles per hour to Knots Converter or browse all speed converters.
Run your own numbers: Miles per hour to Knots Converter