Convert Kilometer to Nautical Mile
Convert kilometers to nautical miles instantly. 1 kilometer = 0.5399568035 nautical mile — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Nautical Mile to Kilometer converter for the reverse conversion.
Units explained
Kilometer
A kilometer is a metric unit of length equal to one thousand meters. It is the standard unit for measuring road distances, geographic distances, and other large-scale measurements in metric countries.
The kilometer was defined alongside the meter in 1795 using the standard SI prefix kilo- (from Greek chilioi, "thousand"), denoting one thousand units.
Kilometers are used worldwide (except the United States and a few others) for road signage, geographic distance, athletic events, and scientific distances at planetary scale. Speed limits in most countries are given in km/h.
Adopted 1795 in France as part of the original metric system; the kilometer became the global standard for road and geographic distance through the 19th and 20th century metric adoption.
Nautical Mile
A nautical mile is a unit of length equal to exactly 1,852 meters, defined as one minute of arc along any meridian of the Earth. It is the standard unit for sea and air navigation worldwide.
Originally defined as one minute of arc along a great circle of the Earth, making it convenient for celestial navigation. The International Hydrographic Organization (IHO) standardized the value at exactly 1,852 meters in 1929.
Nautical miles are used in maritime navigation, aviation, and international law (territorial waters, exclusive economic zones). Speed in nautical miles per hour is called a knot. The nautical mile is distinct from the statute (land) mile.
Defined for celestial navigation since antiquity; standardized to 1,852 m exactly by the IHO in 1929; adopted by the International Civil Aviation Organization (ICAO) for aviation use.
Kilometer to Nautical Mile conversion formula
The relationship between kilometers and nautical miles:
To convert kilometers to nautical miles, multiply the value in kilometers by 0.5399568035. To reverse, multiply nautical miles by 1.852.
How to use this converter
Type a value into the calculator. The result in nautical miles updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Nautical Mile to Kilometer converter for the reverse direction.
Step-by-step: convert kilometers to nautical miles
- Write down the value in kilometers (km).
- Multiply that value by the factor 0.5399568035.
- The product is the equivalent value in nautical miles (nmi).
- To reverse, multiply the nautical mile value by 1.852.
Worked examples
Example 1 — Convert 1 km to nmi:
1 × 0.5399568035 = 0.5399568035 nmi
Example 2 — Convert 100 km to nmi:
100 × 0.5399568035 = 53.9956803456 nmi
Real-world example — Single kilometre to nautical mile
1 km equals 0.540 nautical mile. Land-based coastal-mapping projects converting their km-scale grid into the nmi units used by adjacent maritime authorities do this conversion as part of every boundary harmonisation.
1 km × 0.5399568035 = 0.5399568035 nmi
Real-world example — Long-haul coastal distance
100 km equals 53.996 nmi. Naval logistics planning frequently translates land-based km distances (port-to-port supply routes via road) into nmi (the equivalent open-sea distance).
100 km × 0.5399568035 = 53.9956803456 nmi
Real-world example — Coastal patrol routes
A 50-km coastal patrol route equals about 27 nmi. Coast guards translating land-side route plans (in km) into the maritime-traffic units (nmi) used by their navigation systems do this conversion at every patrol briefing.
50 km × 0.5399568035 = 26.9978401728 nmi
Kilometer to Nautical Mile conversion table
Standard reference values for converting kilometers to nautical miles:
| Kilometer [km] | Nautical Mile [nmi] |
|---|---|
| 0.01 | 0.005399568 |
| 0.1 | 0.0539956803 |
| 1 | 0.5399568035 |
| 2 | 1.0799136069 |
| 3 | 1.6198704104 |
| 4 | 2.1598272138 |
| 5 | 2.6997840173 |
| 10 | 5.3995680346 |
| 20 | 10.7991360691 |
| 30 | 16.1987041037 |
| 40 | 21.5982721382 |
| 50 | 26.9978401728 |
| 100 | 53.9956803456 |
| 500 | 269.9784017279 |
| 1000 | 539.9568034557 |
Frequently asked questions
How many nautical miles is 1 kilometer?
How do I convert kilometers to nautical miles?
How do I convert nautical miles back to kilometers?
How many nautical miles is 100 kilometers?
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Sources & references
Conversion factor (1 km = 0.5399568035 nmi) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.