Calculate distance in nautical miles from speed in knots and travel time, find speed or time, or convert knots to km/h and mph at a constant speed.
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Calculator Functions
| Function | What it does | What it requires |
|---|---|---|
| Distance | Finds the distance covered at a steady speed | Requires the average speed and the travel time |
| Convert speed (knots to km/h or mph) | Converts a speed between knots, km/h, mph and m/s | Requires the speed |
| Average speed | Finds the average speed in knots for a trip | Requires the distance and the travel time |
| Travel time | Finds how long a distance takes at a steady speed | Requires the distance and the average speed |
Speed can be entered in knots, mph or km/h, time in hours or minutes, and distance in nautical miles, statute miles or kilometers. Distance is given in nautical miles with statute miles and kilometers alongside, speed in knots with mph and km/h, and travel time in hours with minutes and days.
Knots to Distance Formulas
| D | Distance (nautical miles) |
| S | Average speed (knots) |
| T | Travel time (hours) |
A knot is one nautical mile per hour [1], so knots times hours gives nautical miles with no conversion factor. A nautical mile is 1,852 meters and a statute mile is 1,609.344 meters [1]. That makes one nautical mile 1.150779 statute miles or 1.852 kilometers.
Distance
The main formula applies directly. 15 knots for 20 hours is 300 nautical miles, which is 345.23 statute miles or 555.6 kilometers. 11 knots for 9 hours 13 minutes (553 minutes) is 101.38 nautical miles.
Convert speed (knots to km/h or mph)
mph = knots × 1.150779 [1]
3.5 knots is 6.482 km/h or 4.028 mph. A speed entered in km/h is converted to knots instead: 30 km/h is 16.199 knots.
Average speed
24 nautical miles in 3 hours is an average of 8 knots. The travel time has to be greater than zero.
Travel time
90 nautical miles at 38 knots takes 90 ÷ 38 = 2.368 hours, or 142.1 minutes. A distance in miles or kilometers is converted to nautical miles first, so 15 km at 0.5 knots is 8.099 nautical miles ÷ 0.5 = 16.2 hours.
Knots to mph and km/h Chart
The last column is the time to cover one nautical mile, in minutes and seconds.
| Knots | mph | km/h | Time per nautical mile |
|---|---|---|---|
| 1 | 1.15 | 1.85 | 60:00 |
| 2 | 2.3 | 3.7 | 30:00 |
| 3 | 3.45 | 5.56 | 20:00 |
| 3.5 | 4.03 | 6.48 | 17:09 |
| 4 | 4.6 | 7.41 | 15:00 |
| 5 | 5.75 | 9.26 | 12:00 |
| 6 | 6.9 | 11.11 | 10:00 |
| 7 | 8.06 | 12.96 | 8:34 |
| 8 | 9.21 | 14.82 | 7:30 |
| 10 | 11.51 | 18.52 | 6:00 |
| 12 | 13.81 | 22.22 | 5:00 |
| 15 | 17.26 | 27.78 | 4:00 |
| 18 | 20.71 | 33.34 | 3:20 |
| 20 | 23.02 | 37.04 | 3:00 |
| 25 | 28.77 | 46.3 | 2:24 |
| 30 | 34.52 | 55.56 | 2:00 |
| 35 | 40.28 | 64.82 | 1:43 |
| 40 | 46.03 | 74.08 | 1:30 |
| 50 | 57.54 | 92.6 | 1:12 |
| 100 | 115.08 | 185.2 | 0:36 |
| 120 | 138.09 | 222.24 | 0:30 |
| 300 | 345.23 | 555.6 | 0:12 |
| 500 | 575.39 | 926 | 0:07 |
Limits of This Estimate
- The speed is treated as a constant average. A trip with speed changes, turns or stops covers less ground than the top speed suggests.
- Speed through the water or the air is not speed over the ground. A current or wind adds to or takes away from the distance made good, so distance over the ground needs speed over the ground.
- Distances are along the path travelled. The result does not plan a route or allow for the curve of a long ocean or air route.
Sources
- NIST Special Publication 811, Appendix B.8: meters in a nautical mile and a statute mile, and the knot as one nautical mile per hour
