How to Convert Nautical miles to Kilometres (nmi to km)
Length conversions come up when reading overseas furniture specs, cycling the Round Island Route in kilometres while a foreign app shows miles, or checking marine distances in the Singapore Strait in nautical miles. This guide shows how to convert nautical miles into kilometres by hand, with examples and a quick-reference table.
The conversion
To convert nautical miles to kilometres, multiply the value by 1.852. To go the other way, divide by the same number (or multiply by 0.5399568035). For a quick estimate, multiply by about 1.9.
Kilometres = nautical miles × 1.852
Worked examples
- 3 nmi = 5.556 km
- 12.5 nmi = 23.15 km
- 75 nmi = 138.9 km
Nautical miles to Kilometres table
| Nautical miles | Kilometres |
|---|---|
| 1 nmi | 1.852 km |
| 2 nmi | 3.704 km |
| 5 nmi | 9.26 km |
| 10 nmi | 18.52 km |
| 20 nmi | 37.04 km |
| 25 nmi | 46.3 km |
| 50 nmi | 92.6 km |
| 100 nmi | 185.2 km |
| 250 nmi | 463 km |
| 500 nmi | 926 km |
| 1,000 nmi | 1,852 km |
Common questions
Is nmi to km exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Kilometres to Nautical miles converter.
Mistakes to avoid
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Forgetting squared and cubed units
Area and volume factors are the length factor squared or cubed, so 1 m² is about 10.76 sq ft, not 3.28.
Background
Unit conversion is simply multiplication by a fixed ratio. The ratio between two units of the same quantity never changes, so once you know it you can convert any value in either direction.
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
A conversion table is handy for common values, but a calculator is faster and avoids interpolation errors for anything in between.
For any value, use the Nautical miles to Kilometres Converter or browse all length converters.
Run your own numbers: Nautical miles to Kilometres Converter