Knots to MPH Converter

Convert knots to miles per hour instantly, with a reference table covering wind speeds, aircraft and vessels.

Knots

Miles per hour

1 kn = 1.1508 mph

Multiply knots by 1.15077945 to get miles per hour.

The link carries the values you entered, so whoever opens it sees the same result. Nothing is stored on our side — the numbers travel in the link itself.

Knots to miles per hour reference table

The conversions people look up most often, rounded to 4 decimal places.

Common knots to miles per hour conversions
Knot (kn)	Mile per hour (mph)
1 kn	1.1508 mph
5 kn	5.7539 mph
10 kn	11.5078 mph
15 kn	17.2617 mph
20 kn	23.0156 mph
25 kn	28.7695 mph
34 kn	39.1265 mph
40 kn	46.0312 mph
50 kn	57.539 mph
64 kn	73.6499 mph
100 kn	115.0779 mph
300 kn	345.2338 mph
500 kn	575.3897 mph

The knots people look up most

15 kn = 17.2617 mph: A good sailing breeze, and the point at which most dinghies start planing.
25 kn = 28.7695 mph: Time to reef, and a strong breeze on the Beaufort scale.
50 kn = 57.539 mph: Storm force, and well past what most small craft should be out in.
135 kn = 155.3552 mph: Airliner approach speed, which is why runways are as long as they are.
470 kn = 540.8663 mph: Typical airliner cruise, quoted in knots because air navigation runs on them worldwide.

How the knots to mph calculation works

A knot is one nautical mile per hour, which makes it 1.15078 mph:

mph = knots × 1.15078

The unit is named for the method: sailors trailed a weighted log on a line knotted at fixed intervals and counted how many knots ran out in a timed interval. The intervals were spaced so the count gave speed directly.

It survives because a nautical mile is one minute of latitude, so speed in knots relates directly to position on a chart in a way mph never can.

Wind speed is where most people meet it. The hurricane categories are defined in knots and then converted, which is why their mph thresholds look arbitrary:

Category	Knots	mph
Tropical storm	34	39
Category 1	64	74
Category 3	96	111
Category 5	137	157

The famous "74 mph" hurricane threshold is just 64 knots rounded.

Other cases:

Sailing. 15 knots of wind is 17.3 mph — a good day. 25 knots is 28.8 mph and time to reef.
Aviation. A cruise speed of 470 knots is 540.9 mph. Approach speeds around 140 knots are 161 mph.
Shipping. A container ship at 20 knots does 23.0 mph, or 552 nautical miles a day.

For a rough figure, add 15%. And note that "knots per hour" is wrong — a knot already is a speed.

Frequently asked questions

Why does the marine forecast use knots when the weather app uses mph?

Because the two forecasts are written for different users. Shipping and inshore waters forecasts give wind in knots, and often as a Beaufort force, since that is what mariners navigate by; land forecasts use mph in Britain and the US and km/h across most of Europe. One weather system is therefore described three ways at once. A force 6 is 22 to 27 knots, or 25 to 31 mph.

Which airspeed does a knots figure refer to?

One of three, and aviation uses knots for all of them. Indicated airspeed is what the instrument reads, true airspeed corrects it for altitude and temperature, and ground speed adds the wind. An aircraft showing 280 knots indicated at cruise may be doing 470 knots true and 540 over the ground with a tailwind, which is 621 mph. Converting is easy; knowing which figure you have is the hard part.

How many metres per second is a knot?

0.5144 m/s exactly, since a knot is 1,852 metres in 3,600 seconds. That makes the mental arithmetic unusually easy: halve the knots for a rough figure in metres per second, and double for the reverse. Engineering wind loads are specified in m/s, so this is the conversion a structural designer reaches for where a sailor reaches for mph.

Knots to MPH Converter