How to Convert Knots
Nautical Speed Conversions Made Simple
Get the ConversionsWeather reports mention 25-knot winds. Ship speeds are given in knots. Aircraft fly at hundreds of knots. But what is a knot in terms of mph or km/h? Understanding knot conversions helps you interpret maritime, aviation, and meteorological data.
What Is a Knot?
A knot is a unit of speed equal to one nautical mile per hour. The nautical mile (1.852 km or 1.151 statute miles) is based on the Earth's geometry—it equals one minute of latitude.
This makes knots ideal for navigation because distance traveled directly relates to position change on charts based on latitude and longitude.
Conversion Table
| Knots | MPH | KM/H | M/S |
|---|---|---|---|
| 5 | 5.8 | 9.3 | 2.6 |
| 10 | 11.5 | 18.5 | 5.1 |
| 15 | 17.3 | 27.8 | 7.7 |
| 20 | 23.0 | 37.0 | 10.3 |
| 25 | 28.8 | 46.3 | 12.9 |
| 30 | 34.5 | 55.6 | 15.4 |
| 40 | 46.0 | 74.1 | 20.6 |
| 50 | 57.5 | 92.6 | 25.7 |
| 100 | 115.1 | 185.2 | 51.4 |
| 200 | 230.2 | 370.4 | 102.9 |
| 500 | 575.5 | 926.0 | 257.2 |
Conversion Formulas
Knots to Other Units
- Knots to mph: Multiply by 1.151
- Knots to km/h: Multiply by 1.852
- Knots to m/s: Multiply by 0.514
Other Units to Knots
- MPH to knots: Divide by 1.151 (or multiply by 0.869)
- KM/H to knots: Divide by 1.852 (or multiply by 0.540)
- M/S to knots: Divide by 0.514 (or multiply by 1.944)
Where Knots Are Used
Maritime
- Ship and boat speeds worldwide
- Current and tide speeds
- Marine weather forecasts
- Nautical charts and navigation
Aviation
- Aircraft airspeed (indicated and true)
- Wind speed aloft
- International flight planning
- Air traffic control
Meteorology
- Wind speed in weather reports
- Hurricane and tropical storm speeds
- Beaufort wind scale (based on knots)
Wind Speed Reference
| Knots | MPH | KM/H | Description |
|---|---|---|---|
| 0-3 | 0-3 | 0-5 | Calm to light air |
| 4-10 | 4-12 | 6-19 | Light breeze |
| 11-21 | 13-24 | 20-39 | Moderate breeze |
| 22-33 | 25-38 | 40-61 | Strong breeze to near gale |
| 34-47 | 39-54 | 62-87 | Gale |
| 48-63 | 55-73 | 88-117 | Storm |
| 64+ | 74+ | 118+ | Hurricane force |
Note: Hurricane category 1 begins at 64 knots (74 mph, 119 km/h)
Aviation Speed Reference
| Aircraft Type | Typical Cruise (knots) | MPH | KM/H |
|---|---|---|---|
| Small prop plane | 100-140 | 115-161 | 185-259 |
| Large turboprop | 250-350 | 288-403 | 463-648 |
| Regional jet | 400-450 | 460-518 | 741-833 |
| Commercial jet | 450-500 | 518-575 | 833-926 |
| Fighter jet | 500-1,200 | 575-1,381 | 926-2,222 |
Conclusion
Knots—nautical miles per hour—remain the standard for maritime, aviation, and meteorological speeds worldwide. To convert to everyday units, multiply knots by 1.151 for mph or 1.852 for km/h. Understanding these conversions helps you interpret wind speeds in weather reports, understand boat or aircraft performance, and navigate the world of maritime and aviation terminology.