To convert knots to mph, multiply by 1.150779: 20 knots = 23.02 mph, 30 knots = 34.52 mph and 10 knots = 11.51 mph. In km/h a knot is exactly 1.852, so 20 knots is 37.04 km/h. For mph to knots, divide by 1.150779. The converter works between knots, mph, km/h and m/s, and shows the Beaufort wind force for wind speeds.
It is for sailors and boaters, pilots, kite and wind surfers reading a marine forecast, and anyone who saw a hurricane or ship speed in knots and wants it in miles or kilometers per hour.
How to use the converter
- Type the speed and pick its unit: knots (kn, kt, kts), mph, km/h or m/s.
- Pick the unit to convert to. All the other units appear below the answer.
- For a wind speed, read the Beaufort force line; it uses whole knots as the scale does.
- Swap to reverse the direction, or Share to send the link.
Formula and source
mph = knots × 1852 ÷ 1609.344 = knots × 1.150779448. NIST Special Publication 811 defines the nautical mile as 1852 m and the knot as one nautical mile per hour, (1852/3600) m/s. NIST Handbook 44 fixes the statute mile at exactly 1.609 344 km. Dividing the two gives the mph factor; it is not a round number, which is why 1.15 is only an approximation.
km/h = knots × 1.852 exactly, and m/s = knots × 0.514444. Going the other way: knots = mph × 0.868976 = km/h ÷ 1.852 = m/s × 1.943844.
Most-searched knots to mph
20 knots to mph
20 knots = 23.016 mph = 37.04 km/h = 10.29 m/s. As a wind, 20 knots is Beaufort force 5, a fresh breeze.
25 knots to mph
25 knots = 28.769 mph = 46.3 km/h = 12.86 m/s. Twenty-five knots of wind is Beaufort force 6, a strong breeze.
30 knots to mph
30 knots = 34.523 mph = 55.56 km/h = 15.43 m/s. Thirty knots is a near gale (force 7).
40 knots to mph
40 knots = 46.031 mph = 74.08 km/h = 20.58 m/s. Forty knots of wind is a gale (force 8).
10 knots to mph
10 knots = 11.508 mph = 18.52 km/h = 5.14 m/s. Ten knots is a gentle breeze.
15 knots to mph
15 knots = 17.262 mph = 27.78 km/h = 7.72 m/s. Fifteen knots is the top of a moderate breeze.
18 knots to mph
18 knots = 20.714 mph = 33.34 km/h = 9.26 m/s. Eighteen knots (kts) sits inside force 5, a fresh breeze.
100 knots to mph
100 knots = 115.078 mph = 185.2 km/h = 51.44 m/s. One hundred knots is an aircraft-scale speed; aviation airspeeds are normally given in knots.
150 knots to mph
150 knots = 172.617 mph = 277.8 km/h = 77.17 m/s. At 150 knots you cover 150 nautical miles, or about 172.6 statute miles, in an hour.
Knots in kilometres per hour
Searches like "kn in km" or "knots into kilometres" usually mean km/h. Multiply by 1.852: 18 kts = 33.34 km/h, 25 kn = 46.3 km/h, 50 kn = 92.6 km/h. As a distance, 1 nautical mile is 1.852 km.
mph to knots
| mph | knots | km/h |
|---|---|---|
| 10 mph | 8.69 | 16.09 |
| 20 mph | 17.38 | 32.19 |
| 30 mph | 26.069 | 48.28 |
| 50 mph | 43.449 | 80.47 |
| 60 mph | 52.139 | 96.56 |
| 100 mph | 86.898 | 160.93 |
Knots to mph and km/h chart
| Knots | mph | km/h | m/s |
|---|---|---|---|
| 1 kn | 1.15 | 1.85 | 0.51 |
| 2 kn | 2.3 | 3.7 | 1.03 |
| 3 kn | 3.45 | 5.56 | 1.54 |
| 4 kn | 4.6 | 7.41 | 2.06 |
| 5 kn | 5.75 | 9.26 | 2.57 |
| 6 kn | 6.9 | 11.11 | 3.09 |
| 7 kn | 8.06 | 12.96 | 3.6 |
| 8 kn | 9.21 | 14.82 | 4.12 |
| 9 kn | 10.36 | 16.67 | 4.63 |
| 10 kn | 11.51 | 18.52 | 5.14 |
| 11 kn | 12.66 | 20.37 | 5.66 |
| 12 kn | 13.81 | 22.22 | 6.17 |
| 13 kn | 14.96 | 24.08 | 6.69 |
| 14 kn | 16.11 | 25.93 | 7.2 |
| 15 kn | 17.26 | 27.78 | 7.72 |
| 16 kn | 18.41 | 29.63 | 8.23 |
| 17 kn | 19.56 | 31.48 | 8.75 |
| 18 kn | 20.71 | 33.34 | 9.26 |
| 19 kn | 21.86 | 35.19 | 9.77 |
| 20 kn | 23.02 | 37.04 | 10.29 |
| 21 kn | 24.17 | 38.89 | 10.8 |
| 22 kn | 25.32 | 40.74 | 11.32 |
| 23 kn | 26.47 | 42.6 | 11.83 |
| 24 kn | 27.62 | 44.45 | 12.35 |
| 25 kn | 28.77 | 46.3 | 12.86 |
| 26 kn | 29.92 | 48.15 | 13.38 |
| 27 kn | 31.07 | 50 | 13.89 |
| 28 kn | 32.22 | 51.86 | 14.4 |
| 29 kn | 33.37 | 53.71 | 14.92 |
| 30 kn | 34.52 | 55.56 | 15.43 |
| 31 kn | 35.67 | 57.41 | 15.95 |
| 32 kn | 36.82 | 59.26 | 16.46 |
| 33 kn | 37.98 | 61.12 | 16.98 |
| 34 kn | 39.13 | 62.97 | 17.49 |
| 35 kn | 40.28 | 64.82 | 18.01 |
| 36 kn | 41.43 | 66.67 | 18.52 |
| 37 kn | 42.58 | 68.52 | 19.03 |
| 38 kn | 43.73 | 70.38 | 19.55 |
| 39 kn | 44.88 | 72.23 | 20.06 |
| 40 kn | 46.03 | 74.08 | 20.58 |
| 41 kn | 47.18 | 75.93 | 21.09 |
| 42 kn | 48.33 | 77.78 | 21.61 |
| 43 kn | 49.48 | 79.64 | 22.12 |
| 44 kn | 50.63 | 81.49 | 22.64 |
| 45 kn | 51.79 | 83.34 | 23.15 |
| 46 kn | 52.94 | 85.19 | 23.66 |
| 47 kn | 54.09 | 87.04 | 24.18 |
| 48 kn | 55.24 | 88.9 | 24.69 |
| 49 kn | 56.39 | 90.75 | 25.21 |
| 50 kn | 57.54 | 92.6 | 25.72 |
| 55 kn | 63.29 | 101.86 | 28.29 |
| 60 kn | 69.05 | 111.12 | 30.87 |
| 64 kn | 73.65 | 118.53 | 32.92 |
| 65 kn | 74.8 | 120.38 | 33.44 |
| 70 kn | 80.55 | 129.64 | 36.01 |
| 75 kn | 86.31 | 138.9 | 38.58 |
| 80 kn | 92.06 | 148.16 | 41.16 |
| 85 kn | 97.82 | 157.42 | 43.73 |
| 90 kn | 103.57 | 166.68 | 46.3 |
| 95 kn | 109.32 | 175.94 | 48.87 |
| 100 kn | 115.08 | 185.2 | 51.44 |
| 120 kn | 138.09 | 222.24 | 61.73 |
| 140 kn | 161.11 | 259.28 | 72.02 |
| 150 kn | 172.62 | 277.8 | 77.17 |
| 160 kn | 184.12 | 296.32 | 82.31 |
| 180 kn | 207.14 | 333.36 | 92.6 |
| 200 kn | 230.16 | 370.4 | 102.89 |
| 250 kn | 287.69 | 463 | 128.61 |
| 300 kn | 345.23 | 555.6 | 154.33 |
| 400 kn | 460.31 | 740.8 | 205.78 |
| 500 kn | 575.39 | 926 | 257.22 |
Beaufort scale in knots, mph and km/h
Marine forecasts give wind as a Beaufort force or in knots. The knot ranges below are the WMO classification as tabled by NOAA's Storm Prediction Center; mph and km/h are converted from those knots.
| Force | Description | Knots | mph | km/h |
|---|---|---|---|---|
| 0 | Calm | < 1 | < 1.2 | < 2 |
| 1 | Light air | 1–3 | 1.2–3.5 | 2–6 |
| 2 | Light breeze | 4–6 | 4.6–6.9 | 7–11 |
| 3 | Gentle breeze | 7–10 | 8.1–11.5 | 13–19 |
| 4 | Moderate breeze | 11–16 | 12.7–18.4 | 20–30 |
| 5 | Fresh breeze | 17–21 | 19.6–24.2 | 31–39 |
| 6 | Strong breeze | 22–27 | 25.3–31.1 | 41–50 |
| 7 | Near gale | 28–33 | 32.2–38 | 52–61 |
| 8 | Gale | 34–40 | 39.1–46 | 63–74 |
| 9 | Strong gale | 41–47 | 47.2–54.1 | 76–87 |
| 10 | Storm | 48–55 | 55.2–63.3 | 89–102 |
| 11 | Violent storm | 56–63 | 64.4–72.5 | 104–117 |
| 12 | Hurricane | 64+ | 73.6+ | 119+ |
The Met Office lists the mean wind for each force, for example 24 knots at force 6 and 37 knots at force 8, which sit inside these ranges.
Why "knots per hour" is wrong
A knot already includes "per hour": it means one nautical mile per hour. Saying a boat does 20 knots per hour would mean its speed rises by 20 knots every hour, an acceleration. The same goes for "knots per hour to mph": the conversion is simply knots × 1.1508.
Worked examples
Marine forecast
A forecast warns of 35-knot gusts. 35 × 1.1508 = 40.3 mph, or 65 km/h: gale force on the Beaufort scale.
Boat passage time
A 42-nautical-mile crossing at 7 knots takes 42 ÷ 7 = 6 hours. In land terms the boat is doing 8.1 mph over 77.8 km.
Aircraft speed
A light aircraft cruises at 120 knots true airspeed: 138.1 mph, 222 km/h. Remember ground speed also depends on the wind.
Common mistakes
- Treating a knot as a mile per hour. 30 knots is 34.5 mph, not 30.
- Dividing when you should multiply. The mph number is always about 15% bigger than the knot number.
- Using 1.15 for large speeds. 500 kn × 1.15 = 575 mph, but the exact answer is 575.4 mph.
- Mixing nautical and statute miles. Chart distances are nautical miles (1.852 km); road distances are statute miles (1.609 km).
Related: km/h to mph, km to miles and running pace converter.
Frequently asked questions
How many mph is 1 knot?
1 knot = 1.150779 mph. It is defined as 1 nautical mile (1,852 m) per hour, and a statute mile is 1,609.344 m.
How do you convert knots to mph?
Multiply knots by 1.150779. 20 knots × 1.150779 = 23.016 mph. A quick mental version is knots × 1.15.
How do you convert mph to knots?
Divide mph by 1.150779 (or multiply by 0.868976). 100 mph = 86.898 knots.
How many km/h is a knot?
Exactly 1.852 km/h. So 10 knots = 18.52 km/h and 30 knots = 55.56 km/h.
What does 'knots per hour' mean?
Nothing useful: a knot is already a speed (nautical miles per hour), so 'knots per hour' would be an acceleration. Say 20 knots, not 20 knots per hour.
Why do boats and planes use knots?
One nautical mile was based on one minute of latitude, so speeds in knots fit charts marked in degrees and minutes. It is now fixed at exactly 1,852 m.
What is 30 knots in mph?
30 knots = 34.523 mph = 55.56 km/h, a near gale on the Beaufort scale.
What is kt or kts?
kt and kts are abbreviations for knot and knots; kn is the symbol NIST SP 811 uses. They all mean the same unit.
How many m/s is a knot?
1 knot = 1852 ÷ 3600 = 0.514444 m/s, so 10 knots ≈ 5.14 m/s. A rough rule is knots ÷ 2 ≈ m/s.
At what wind speed in knots is it a gale?
Beaufort force 8 (gale) is 34–40 knots; force 12 (hurricane force) is 64 knots and above.
Sources & method
- NIST SP 811, Chapter 5, Table 9 — nautical mile = 1852 m; knot = 1 nautical mile per hour = (1852/3600) m/s
- NIST SP 811, Appendix B.8 — knot = 0.514 444 m/s; mile per hour = 1.609 344 km/h (exact)
- NIST Handbook 44 (2026), Appendix C — 1 international nautical mile = 1 852 m (exactly); 1 mile = 1.609 344 km
- NOAA Storm Prediction Center — Beaufort wind force scale (knots, WMO classification)
- UK Met Office — Beaufort wind force scale (mean speeds in knots and m/s)
Results are estimates for general information. Found an error? It helps everyone — see our methodology.