Knots to Mph
Enter knots to get miles per hour. A knot is a nautical mile (1,852 m) per hour, so 1 kn is about 1.151 mph.
Formula: mph = kn × 1.15077944802
1.151
Miles per hour in one knot
Multiply knots by 1.150779 to get mph. A knot is one nautical mile of 1,852 m per hour; a mph is one statute mile of 1,609.344 m per hour.
Knots to mph table
| Knots (kn) | Miles per hour (mph) |
|---|---|
| 1 | 1.150779 |
| 2 | 2.301559 |
| 3 | 3.452338 |
| 4 | 4.603118 |
| 5 | 5.753897 |
| 6 | 6.904677 |
| 7 | 8.055456 |
| 8 | 9.206236 |
| 9 | 10.35702 |
| 10 | 11.50779 |
| Knots (kn) | Miles per hour (mph) |
|---|---|
| 12 | 13.80935 |
| 15 | 17.26169 |
| 20 | 23.01559 |
| 25 | 28.76949 |
| 30 | 34.52338 |
| 40 | 46.03118 |
| 50 | 57.53897 |
| 60 | 69.04677 |
| 75 | 86.30846 |
| 100 | 115.0779 |
Statute miles and nautical miles
Both units are miles per hour, but the miles differ. The nautical mile of 1,852 m is about 15 % longer than the statute mile on road signs, so every knot is a little over one mph. NIST lists both definitions in SP 811.
The US National Hurricane Center gives wind speeds in knots and mph side by side; on its Saffir-Simpson scale a Category 1 hurricane starts at 64 kn, published as 74 mph.
Airport weather reports (METARs) give wind in knots in most countries, though a few report it in meters per second.
Speeds you may see
- 25 kn = 28.8 mph, a brisk sailing breeze
- 34 kn = 39.1 mph, tropical storm force
- 64 kn = 73.7 mph, hurricane force
- 150 kn = 172.6 mph, a light aircraft at cruise
Converting back and to metric
To go from mph to knots, divide by 1.150779 or multiply by 0.868976. For metric speeds, one knot is exactly 1.852 km/h; knots to km/h has that table, and mph to km/h covers road speeds.
Mental math works well here: add 15 % to the knots. 20 kn plus 3 gives 23 mph, against an exact 23.02. Going the other way, take about 13 % off the mph figure. These shortcuts are fine for reading a forecast, but use the exact factor for navigation or any figure you publish, since small errors grow over long passages.
Boat speedometers and GPS units can usually show knots, mph or km/h, and switching the display is often easier than converting by hand while underway. Keep the unit the same as the one used on your chart and in the tide tables.
Knots to mph questions
What is one knot in miles per hour?
1 kn is 1.150779 mph, usually rounded to 1.15.
How fast is 40 knots in mph?
40 kn is 46.03 mph.
Why do marine forecasts use knots?
Charts and navigation work in nautical miles, so speeds in knots fit straight into distance and time sums at sea.
Is 100 knots faster than 100 mph?
Yes. 100 kn is 115.08 mph.