Knots to mph converter, boat, wind and plane speeds in miles per hour.

To convert knots to mph, multiply by 1.15078. So 10 knots is 11.51 mph, 20 knots is 23.02 mph and 100 knots is 115.1 mph. A knot is one nautical mile per hour, and a nautical mile (1,852 m) is longer than a statute mile (1,609.344 m), so the mph number is always bigger than the knot number.

How to use the converter

1. Type the amount in the Knots (kn) box. A decimal such as 2.5 or a fraction such as 3/4 works.
2. The big result shows Miles per hour (mph). Use Decimals in the side column to fix the number of places.
3. The cards under the result give the same speed in other units.
4. Type in the second box, or press the swap button, to convert miles per hour to knots instead.
5. Click a row in Common values to load it. Copy result, Copy link, Copy table and Print chart keep the answer. Start again resets the box.

"Knots per hour" is a slip

People type "knots per hour" because "knots" sounds like a distance. It is not. One knot already means one nautical mile every hour. Saying "20 knots per hour" would describe a speed that grows by 20 knots each hour, which is an acceleration. If you meant a steady speed, enter it in the first box as knots and ignore the "per hour".

The factor, worked out

1 knot = 1,852 m in an hour. 1 mile = 1,609.344 m. So 1 knot = 1,852 ÷ 1,609.344 = 1.150779 mph. The exact fraction is 57,875 ÷ 50,292. For a quick estimate in your head, add about 15 percent: 20 knots × 1.15 = 23 mph, against the true 23.02 mph. The shortcut is off by only 0.07 percent.

Knots to mph, 5 to 40

Worked examples

• A boat at 12 knots. 12 × 1.15078 = 13.81 mph.
• A 3 hour trip at 12 knots. 12 × 3 = 36 nautical miles, which is 36 × 1,852 ÷ 1,609.344 = 41.43 statute miles.
• A wind of 25 knots. 28.77 mph, or 46.3 km/h.
• A speed of 450 knots. 517.9 mph.
• Back the other way. 60 mph = 52.14 knots. Press the swap button and type 60.

Where the numbers come from

NIST SP 811, Appendix B.8 lists the international mile as 1,609.344 m, the nautical mile as 1,852 m, and the knot as one nautical mile per hour (0.5144444 m/s). It also gives 1 mile per hour as 1.609344 km/h. Checked 24 Oct 2026. The converter keeps these as exact fractions and rounds only the last digit shown.

Mistakes to avoid

The first is mixing the two miles: a nautical mile is about 15 percent longer than a statute mile, so 10 nautical miles is not 10 miles. The second is dividing when you should multiply. Going from knots to mph the number grows, so if your answer is smaller than the number you typed, the factor was upside down. The third is the unit label: "kt" and "kn" both mean knots.

Related pages: Mph to knots, Kph to mph, and Unit converter.