Kilometers to Nautical Miles Converter (km to nmi)
1 km = 0.539957 nmi. Convert kilometers to nautical miles for passage planning, flight planning and sea crossings, with km and nmi charts.
Nautical Mile (nmi) = Kilometer (km) × 0.539956803456
Kilometer (km): The kilometre is 1,000 metres. One international mile is exactly 1.609344 km; to convert kilometres to miles, divide by 1.609344.
Nautical Mile (nmi): The international nautical mile is exactly 1852 metres. It was chosen because it is close to one minute of latitude, and it is used in sea and air navigation together with the knot (one nautical mile per hour).
| Kilometer (km) | Nautical Mile (nmi) |
|---|---|
| 1 | 0.539956803456 |
| 5 | 2.69978401728 |
| 10 | 5.39956803456 |
| 25 | 13.4989200864 |
| 50 | 26.9978401728 |
| 100 | 53.9956803456 |
Distances read off a road map, a GPS track or a metric chart plotter often have to go into a log, a passage plan or a flight plan in nautical miles. Travel guides and maps quote ferry routes, bridges and tunnels in kilometers, while the charts at the helm or in the cockpit read nautical miles. One kilometer is about 0.54 nautical miles, because the nautical mile is defined as exactly 1,852 m.
Speed follows the same factor. A boat or aircraft covering one nautical mile per hour is doing one knot, so a speed in km/h converts to knots exactly as kilometers convert to nautical miles; one knot is therefore exactly 1.852 km/h, and the speed converter does the arithmetic for you.
How to use this tool
- Type a value in the Kilometer box to see it in nautical miles, or type in the Nautical Mile box to convert the other way.
- Press ⇄ to swap the two units, or Load example for a typical value.
- Check the charts below for common values; for other units, open the Length converter.
Formula
Nautical Mile (nmi) = Kilometer (km) × 0.539956803456
Kilometer (km) = Nautical Mile (nmi) × 1.852
Both factors come from exact definitions: 1 nautical mile = 1.852 kilometers and 1 kilometer = 0.539956803456 nautical miles (shown to 12 significant digits).
Example
Two conversions worked with the same factors the converter uses:
50 km × 0.539956803456 ≈ 26.9978 nmi
20 nmi × 1.852 = 37.04 km
Kilometer to Nautical Mile chart
Common values from kilometers to nautical miles, rounded to four decimal places.
| Kilometer (km) | Nautical Mile (nmi) |
|---|---|
| 0.5 | 0.27 |
| 1 | 0.54 |
| 1.852 | 1 |
| 2 | 1.0799 |
| 5 | 2.6998 |
| 8 | 4.3197 |
| 10 | 5.3996 |
| 15 | 8.0994 |
| 25 | 13.4989 |
| 30 | 16.1987 |
| 40 | 21.5983 |
| 50 | 26.9978 |
| 75 | 40.4968 |
| 100 | 53.9957 |
| 120 | 64.7948 |
| 150 | 80.9935 |
| 250 | 134.9892 |
| 400 | 215.9827 |
| 600 | 323.9741 |
| 800 | 431.9654 |
| 1,500 | 809.9352 |
| 5,000 | 2,699.78 |
| 10,000 | 5,399.57 |
Nautical Mile to Kilometer chart
The reverse direction for values people often look up.
| Nautical Mile (nmi) | Kilometer (km) |
|---|---|
| 0.25 | 0.463 |
| 1 | 1.852 |
| 4 | 7.408 |
| 6 | 11.112 |
| 8 | 14.816 |
| 18 | 33.336 |
| 30 | 55.56 |
| 40 | 74.08 |
| 45 | 83.34 |
| 80 | 148.16 |
| 120 | 222.24 |
| 400 | 740.8 |
Long crossings and distances quoted in kilometers
| Item | Kilometer (km) | Nautical Mile (nmi) |
|---|---|---|
| Channel Tunnel, total length | 50.45 | 27.2408 |
| Seikan Tunnel, total length | 53.85 | 29.0767 |
| Øresund Bridge, length | 7.845 | 4.236 |
| Hong Kong–Zhuhai–Macao Bridge, total length | 55 | 29.6976 |
| Marathon race distance | 42.195 | 22.7835 |
| Earth's equatorial circumference (WGS 84) | 40,075 | 21,638.77 |
| Pole to equator, by the 1790s meter definition | 10,000 | 5,399.57 |
Quick mental estimate
Halve the kilometers and add 8% of that half: 100 km → 50 + 4 = 54 nmi, while the exact figure is 53.996 nmi. The shortcut multiplies by 0.54, which is within 0.01% of the true factor.
Use the converter or the charts when the exact figure matters.
The two units
Kilometer (km): The kilometre is 1,000 metres. One international mile is exactly 1.609344 km; to convert kilometres to miles, divide by 1.609344.
Nautical Mile (nmi): The international nautical mile is exactly 1852 metres. It was chosen because it is close to one minute of latitude, and it is used in sea and air navigation together with the knot (one nautical mile per hour).
Frequently asked questions
How many nautical miles is 100 km?
About 54.0 nmi (53.9957 to four decimals). For planning, 100 km and 54 nmi can be treated as the same distance; the exact factor is 1 divided by 1.852.
Why do pilots and sailors use nautical miles instead of kilometers?
A nautical mile is close to one minute of latitude, so distances can be measured on a chart against its latitude scale, and the unit pairs with the knot for speed. It is the standard distance unit across nearly all international shipping and aviation.
How do I convert km/h to knots?
Divide km/h by 1.852, or multiply by about 0.54. A speed of 90 km/h is about 48.6 knots, and wind speeds forecast in km/h convert the same way.
How precise is the result?
The converter uses the exact definitions above with browser floating-point arithmetic and shows up to 12 significant digits. The charts round to four decimal places for reading.
Sources
Last updated:
Page address with these inputs: https://kakao.mobile/tools/kilometer-to-nautical-mile-converter/
Cite or embed this tool
kakaoCalc. (2026, November 8). Kilometers to Nautical Miles Converter (km to nmi). https://kakao.mobile/tools/kilometer-to-nautical-mile-converter/
“Kilometers to Nautical Miles Converter (km to nmi).” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/kilometer-to-nautical-mile-converter/.
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