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Knots to mph and mph to knots converter

Knots to mph: 1 knot = 1.1508 mph (exactly 1.150779448), so 10 kn = 11.5078 mph. Type knots and the mph appear as you type, with km/h and m/s underneath; mph to knots works in the same box.

Example: Speed 10 · Direction: Knots to mph (kn → mph) → Answer: 10 kn = 11.5078 mph. Source: NIST SP 811, Appendix B.8 – nautical mile = 1852 m (exact), knot = 1 nautical mile per hour. Updated: .

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Result

Answer
10 kn = 11.5078 mph
Other units
In km/h: 18.52. In m/s: 5.1444.
Working
10 kn × 1.150779448 = 11.5078 mph
Quick check in your head
10 × 1.15 ≈ 11.5 mph (exact: 11.5078 mph). Adding 15 % comes out only 0.07 % too low.
Conversion chart
knmph
11.1508
22.3016
33.4523
55.7539
89.2062
1011.5078
1213.8094
1517.2617
2023.0156
2528.7695
3034.5234
3439.1265
4046.0312
5057.539
6473.6499
100115.0779
200230.1559
450517.8508
Speeds worth knowing
Speedknmph
Beaufort 4, moderate breeze (11 kn)1112.6586
Container ship cruising, about 20 kn2023.0156
Beaufort 8, gale begins (34 kn)3439.1265
Beaufort 10, storm begins (48 kn)4855.2374
Hurricane threshold (64 kn)6473.6499
Category 5 hurricane threshold (137 kn)137157.6568
Airliner cruising, about 450 kn450517.8508
1 knot is 1 nautical mile per hour: 1,852 m per hour, 1.852 km/h or 1.150779448 mph, exact. Say "knots", not "knots per hour".

How it is calculated

The conversion

mph = knots × 1.150779448, and knots = mph ÷ 1.150779448. A knot is one nautical mile per hour, and the international nautical mile is exactly 1,852 m, against 1,609.344 m for a statute mile (the ratio is the factor). So 25 kn = 28.7695 mph and, back again, 60 mph = 52.1386 kn. In metric, 1 knot is 1.852 km/h.

Weather: one wind, two numbers

Marine forecasts give wind in knots; land forecasts and the US National Hurricane Center give miles per hour, and often both. Beaufort force 8, a gale, starts at 34 kn, which is 39.1265 mph. A storm (force 10) starts at 48 kn (55.2374 mph). A hurricane starts at 64 kn, which is 73.6499 mph and is rounded to the familiar 74 mph. In the other direction, 74 mph is 64.3042 kn, and a Category 5 storm of 157 mph is 136.4293 kn, which the NHC rounds to 137.

Boats and aircraft

A ship doing 20 kn is making 23.0156 mph or 37 km/h. Airliners cruise at about 450 to 490 kn: 517.8508 mph for 450 kn. Pilots and sailors never say “knots per hour”, because the knot already contains the hour; that phrase would be an acceleration.

Where the knot comes from

Sailors measured speed with a log line trailing behind the ship, with knots tied at equal spacing, and counted how many ran out in a fixed time. The unit survived the instruments. The meter-based definition of the nautical mile as 1,852 m, one minute of latitude on average, was adopted internationally in 1929 (the US followed in 1954, the UK in 1970).

Quick estimate

Add 15 %: 30 kn is about 34.5 mph (exact: 34.5234). This shortcut is off by less than 0.1 %, so it works for nearly any practical purpose. For km/h multiply by 1.85. See also kph to mph for road speeds.

Frequently asked questions

How many mph is 1 knot?

1 kn = 1.1508 mph, exactly 1.150779448 mph or 1.852 km/h.

How do I convert knots to mph?

Multiply by 1.1508, or add 15 %. For 10 knots: 10 kn = 11.5078 mph.

What is 74 mph in knots?

74 mph = 64.3042 kn, i.e. about 64 knots, the hurricane threshold.

Is a knot faster than a mile per hour?

Yes, by about 15 %. A knot is based on the nautical mile (1,852 m), which is longer than the statute mile (1,609.344 m).

Why is it wrong to say knots per hour?

A knot is already a distance per hour (one nautical mile per hour). "Knots per hour" would mean a change of speed, an acceleration.

Sources and legal basis

As of: · Editorial policy

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