How to Convert Kilometres to Nautical miles (km to nmi)
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 kilometres into nautical miles by hand, with examples and a quick-reference table.
The conversion
To convert kilometres to nautical miles, multiply the value by 0.5399568035. To go the other way, divide by the same number (or multiply by 1.852). For a quick estimate, multiply by about 0.54.
Nautical miles = kilometres × 0.5399568035
Worked examples
- 3 km = 1.6199 nmi
- 12.5 km = 6.7495 nmi
- 75 km = 40.4968 nmi
Kilometres to Nautical miles table
| Kilometres | Nautical miles |
|---|---|
| 1 km | 0.539957 nmi |
| 2 km | 1.0799 nmi |
| 5 km | 2.6998 nmi |
| 10 km | 5.3996 nmi |
| 20 km | 10.7991 nmi |
| 25 km | 13.4989 nmi |
| 50 km | 26.9978 nmi |
| 100 km | 53.9957 nmi |
| 250 km | 134.9892 nmi |
| 500 km | 269.9784 nmi |
| 1,000 km | 539.9568 nmi |
Common questions
Is km to nmi 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 Nautical miles to Kilometres converter.
Mistakes to avoid
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.
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.
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Background
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
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.
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.
For any value, use the Kilometres to Nautical miles Converter or browse all length converters.
Run your own numbers: Kilometres to Nautical miles Converter