Boat Speed Knots Converter
Convert boat speed between knots, miles per hour (mph), kilometres per hour (km/h), and metres per second (m/s). Knots are the international standard for maritime and aviation speed, defined as one nautical mile per hour. One nautical mile is exactly 1,852 metres, as fixed by the International Hydrographic Organization. Enter a speed in any unit and all others update instantly.
Knot conversion formulas
mph = knots × 1.15078
km/h = knots × 1.852
m/s = knots × 0.514444
These conversion factors come from the international definition of the nautical mile (1,852 m) and the statute mile (1,609.344 m), as published by NIST Special Publication 811.
Beaufort wind scale reference
| Beaufort | Description | Knots | mph |
|---|---|---|---|
| 0 | Calm | < 1 | < 1 |
| 1 | Light air | 1-3 | 1-3 |
| 2 | Light breeze | 4-6 | 5-7 |
| 3 | Gentle breeze | 7-10 | 8-12 |
| 4 | Moderate breeze | 11-16 | 13-18 |
| 5 | Fresh breeze | 17-21 | 19-24 |
| 6 | Strong breeze | 22-27 | 25-31 |
| 7 | Near gale | 28-33 | 32-38 |
| 8 | Gale | 34-40 | 39-46 |
| 9 | Severe gale | 41-47 | 47-54 |
| 10 | Storm | 48-55 | 55-63 |
Knots converter: frequently asked questions
What is a knot in boat speed?
A knot is one nautical mile per hour. One nautical mile equals 1,852 metres (6,076 feet), which is slightly longer than a statute mile. Knots are the standard unit of speed for ships, boats, and aircraft worldwide.
How do I convert knots to miles per hour?
Multiply knots by 1.15078 to get miles per hour. For example, 10 knots equals 11.51 mph. The reverse: multiply mph by 0.868976 to get knots.
How do I convert knots to kilometres per hour?
Multiply knots by 1.852 to get km/h. One knot equals exactly 1.852 km/h by international definition. For example, 20 knots equals 37.04 km/h.
Why do boats and aircraft use knots instead of mph?
Knots are tied directly to degrees of latitude on the Earth's surface, making navigation with charts and compasses more intuitive. One nautical mile is one arcminute of latitude, so distances and positions on a chart relate directly to speed in knots.
What is the conversion between knots and metres per second?
Multiply knots by 0.514444 to get metres per second. For example, 15 knots equals 7.72 m/s. This conversion is useful in engineering and physics calculations.
Official sources
- NIST Special Publication 811: Guide for the Use of the International System of Units (SI).
- National Oceanic and Atmospheric Administration (NOAA): Beaufort Wind Scale.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.