How to convert miles per hour to knots
- Take the value in miles per hour.
- Use the formula knots = miles per hour × 0.8689762419.
- For example, 10 mph is 8.69 kn.
About miles per hour and knots
A knot is one nautical mile (1,852 m) per hour, and a mile is 1,609.344 m, so 1 mph is 0.868976 knots. Multiply mph by 0.869 to get knots. For a quick estimate take off 13%: 50 mph is about 43.5 knots against the exact 43.45.
You need this when a US news report, a road sign or a car speedometer gives miles per hour and a chart, a boat GPS or a marine or aviation forecast works in knots. Pilots and sailors in the US switch between the two all the time, since wind on land is reported in mph and wind at sea in knots.
Examples
- 10 mph (a 10 mph breeze, an illustrative forecast value) is 8.69 kn
- 39 mph (the start of tropical storm winds in US advisories) is 33.89 kn
- 111 mph (the start of Category 3, a major hurricane) is 96.46 kn
- 157 mph (the start of Category 5 on the Saffir-Simpson scale) is 136.43 kn
Miles per hour to knots chart
| Miles per hour (mph) | Knots (kn) |
|---|---|
| 1 | 0.869 |
| 2 | 1.74 |
| 5 | 4.34 |
| 10 | 8.69 |
| 15 | 13.03 |
| 20 | 17.38 |
| 25 | 21.72 |
| 30 | 26.07 |
| 35 | 30.41 |
| 39 | 33.89 |
| 40 | 34.76 |
| 45 | 39.1 |
| 50 | 43.45 |
| Miles per hour (mph) | Knots (kn) |
|---|---|
| 55 | 47.79 |
| 60 | 52.14 |
| 70 | 60.83 |
| 74 | 64.3 |
| 80 | 69.52 |
| 96 | 83.42 |
| 100 | 86.9 |
| 111 | 96.46 |
| 130 | 112.97 |
| 157 | 136.43 |
| 200 | 173.8 |
| 300 | 260.69 |
| 500 | 434.49 |