Knots to Miles per Hour (kn to mph)
A knot is one nautical mile per hour. The international nautical mile is exactly 1,852 m and the statute mile exactly 1,609.344 m (NIST SP 811), so 1 knot = 1,852 ÷ 1,609.344 = 1.150779 mph. Multiply knots by 1.15 for a quick answer: 20 knots is 23.0 mph.
Formula
mph = knots × 1.150779 (= knots × 1,852 ÷ 1,609.344)
Example: 10 knots = 11.5078 miles per hour.
Knots to Miles per Hour chart
| knots | miles per hour |
|---|---|
| 1 | 1.15078 |
| 5 | 5.7539 |
| 6 | 6.90468 |
| 10 | 11.5078 |
| 15 | 17.2617 |
| 20 | 23.0156 |
| 25 | 28.7695 |
| 30 | 34.5234 |
| 34 | 39.1265 |
| 40 | 46.0312 |
| 50 | 57.539 |
| 64 | 73.6499 |
| 83 | 95.5147 |
| 96 | 110.475 |
| 100 | 115.078 |
| 113 | 130.038 |
| 137 | 157.657 |
| 250 | 287.695 |
Good to know
Hurricanes: the US National Hurricane Center measures wind in knots and publishes mph. A tropical storm starts at 34 kt (39 mph); the Saffir-Simpson categories begin at 64 kt (74 mph, Category 1), 83 kt (96 mph), 96 kt (111 mph), 113 kt (130 mph) and 137 kt (157 mph, Category 5). The chart below includes each threshold.
Boats and aircraft: a sailboat cruising at 6 knots is doing 6.9 mph; a fast ferry at 35 knots is doing 40.3 mph. Below 10,000 feet in US airspace aircraft are limited to 250 knots indicated airspeed — about 288 mph.
Why knots: one nautical mile is one minute of latitude, so a navigator moving at 1 knot covers one minute of latitude per hour. That makes chart work simple, which is why ships, aircraft and weather services kept the unit. Never say 'knots per hour' — a knot already means per hour.
Frequently asked questions
How many mph is 1 knot?
1 knot is 1.150779 mph.
How fast is 30 knots in mph?
30 knots is 34.52 mph.
Is a knot faster than a mile per hour?
Yes. A knot is about 15% faster than 1 mph because a nautical mile (1,852 m) is longer than a statute mile (1,609.344 m).
How many knots is a Category 5 hurricane?
137 knots or more, which is 157 mph or more on the Saffir-Simpson scale.