How to Convert Knots to MPH
Master the knots to MPH conversion with the exact formula, worked examples for aviation and sailing, and a quick reference chart.
Last updated: 2026-03-15
The Knots to MPH Formula
The conversion from knots to miles per hour is a simple multiplication:
MPH = Knots × 1.15078
A knot is defined as one nautical mile per hour. One nautical mile equals exactly 1,852 meters, while one statute mile equals 1,609.344 meters. The ratio 1,852 / 1,609.344 = 1.15078 gives us the conversion factor.
Step-by-Step Examples
Example 1: Wind Advisory at 25 Knots
- Calculation: 25 × 1.15078 = 28.77 mph.
- Result: 25-knot winds are approximately 29 mph.
Example 2: Sailboat Cruising at 7 Knots
- Calculation: 7 × 1.15078 = 8.06 mph.
- Result: 7 knots = approximately 8 mph.
Example 3: Aircraft Speed of 250 Knots
- Calculation: 250 × 1.15078 = 287.7 mph.
- Result: 250 knots = approximately 288 mph.
Speed Reference Table
| Knots | MPH | km/h | Context |
|---|---|---|---|
| 5 | 5.8 | 9.3 | Light breeze |
| 10 | 11.5 | 18.5 | Gentle breeze / sailing |
| 20 | 23.0 | 37.0 | Fresh breeze |
| 34 | 39.1 | 63.0 | Gale force (Beaufort 8) |
| 50 | 57.5 | 92.6 | Storm force winds |
| 64 | 73.6 | 118.5 | Hurricane threshold |
| 100 | 115.1 | 185.2 | Small plane approach |
| 250 | 287.7 | 463.0 | Jet cruise (low) |
| 450 | 517.9 | 833.4 | Commercial jet cruise |
Real-World Applications
Weather Forecasts
The National Weather Service reports marine wind speeds in knots. Knowing the conversion helps landlubbers understand the severity of wind warnings. A small craft advisory at 25 knots means winds of about 29 mph.
Aviation
Pilots worldwide use knots for airspeed and ground speed. Air traffic control instructions, airport weather reports (METARs), and flight plans all use knots. Passenger-facing displays, however, often show mph or km/h.
Sailing and Boating
Marine charts, GPS plotters, and logbooks use knots as the standard speed unit. A recreational sailboat averaging 6 knots (6.9 mph) is making good progress. Speed through water and speed over ground may differ due to currents.
Quick Mental Conversion
For a quick estimate, add 15% to the knot value to get mph. So 20 knots is approximately 20 + 3 = 23 mph. This is accurate to within 1%. For precise results, use our speed converter.