Knots to Miles per Hour Converter (kn to mph)

Ships, aircraft and weather services measure speed in knots, one nautical mile per hour, but American news reports and road-minded readers think in miles per hour. A nautical mile is exactly 1,852 m against the statute mile's 1,609.344 m, so a knot is about 15% faster than a mile per hour, and any speed looks smaller in knots than in mph.

Hurricanes are the most common reason to convert. The National Hurricane Center estimates wind speed in knots, in 5-knot steps, and its public advisories give the mph equivalent; the Saffir-Simpson scale lists both. Boaters and pilots meet the same split, since charts, marine forecasts and airspeed indicators use knots while intuition from driving runs in mph.

How to use this tool

1. Type a value in the Knot box to see it in miles per hour, or type in the Mile per Hour box to convert the other way.
2. Press ⇄ to swap the two units, or Load example for a typical value.
3. Check the charts below for common values; for other units, open the Speed converter.

Formula

Mile per Hour (mph) = Knot (kn) × 1.15077944802

Knot (kn) = Mile per Hour (mph) × 0.868976241901

Both factors come from exact definitions: 1 mile per hour = 0.868976241901 knots and 1 knot = 1.15077944802 miles per hour (shown to 12 significant digits).

Example

Two conversions worked with the same factors the converter uses:

64 kn × 1.15077944802 ≈ 73.6499 mph

30 mph × 0.868976241901 ≈ 26.0693 kn

Knot to Mile per Hour chart

Common values from knots to miles per hour, rounded to four decimal places.

Mile per Hour to Knot chart

The reverse direction for values people often look up.

Speeds and limits set in knots

Quick mental estimate

Add 15% to the knots: 40 kn → 40 + 6 = 46 mph, against an exact 46.03 mph. The 1.15 factor is only about 0.07% low, so the shortcut is good enough for any forecast or logbook.

Use the converter or the charts when the exact figure matters.

The two units

Knot (kn): A knot is one nautical mile per hour. The international nautical mile is exactly 1852 m, so 1 knot is 1.852 km/h (about 0.5144 m/s); it is the standard speed unit at sea, in aviation and in marine weather.

Mile per Hour (mph): Miles per hour is the road-speed unit used in the United States and the United Kingdom. The international mile is exactly 1609.344 m, so 1 mph is exactly 0.44704 m/s or 1.609344 km/h.