Industry Guide
Nautical Measurements for Boating and Sailing
Complete reference for nautical units: nautical miles, knots, fathoms, and their conversions to everyday units.
Last updated: 2026-03-15
Nautical Unit Conversions
| Nautical Unit | Metric | Imperial |
|---|---|---|
| 1 nautical mile | 1,852 m / 1.852 km | 6,076 ft / 1.151 mi |
| 1 knot | 1.852 km/h | 1.151 mph |
| 1 fathom | 1.8288 m | 6 ft |
| 1 cable (US) | 219.46 m | 720 ft |
| 1 cable (Imperial) | 185.32 m | 608 ft |
| 1 league (nautical) | 5,556 m | 3 nmi |
Speed Reference
| Knots | MPH | KM/H | Context |
|---|---|---|---|
| 3-5 | 3.5-5.8 | 5.6-9.3 | Sailing dinghy |
| 5-8 | 5.8-9.2 | 9.3-14.8 | Cruising sailboat |
| 15-25 | 17.3-28.8 | 27.8-46.3 | Motorboat |
| 20-30 | 23.0-34.5 | 37.0-55.6 | Commercial ship |
| 30+ | 34.5+ | 55.6+ | Fast ferry / military |
Why Nautical Miles?
One nautical mile equals one minute of arc of latitude on Earth. This makes distance calculations from charts straightforward: the latitude scale on a chart's border directly measures nautical miles. One degree of latitude is 60 nautical miles, regardless of location.
Beaufort Wind Scale
| Force | Knots | MPH | Description |
|---|---|---|---|
| 0 | <1 | <1 | Calm |
| 3 | 7-10 | 8-12 | Gentle breeze |
| 5 | 17-21 | 19-24 | Fresh breeze |
| 7 | 28-33 | 32-38 | Near gale |
| 10 | 48-55 | 55-63 | Storm |
| 12 | 64+ | 74+ | Hurricane |
Convert speeds with our speed converter.