Nautical Miles to Kilometers
Convert nautical miles (nmi) to kilometers (km). Both measure distance and dimension, and the conversion comes up in construction, navigation, sports work.
The Formula
``
kilometers = nautical miles × 1.852
nautical miles = kilometers × 0.539956803456
`
One nautical mile is 1.852 kilometers, and one kilometer is 0.539957 nautical miles.
Conversion Table
| Nautical Miles | Kilometers |
|---|---|
| 1 nmi | 1.852 km |
| 2 nmi | 3.704 km |
| 5 nmi | 9.26 km |
| 10 nmi | 18.52 km |
| 25 nmi | 46.3 km |
| 50 nmi | 92.6 km |
| 100 nmi | 185.2 km |
| 500 nmi | 926 km |
| 1,000 nmi | 1,852 km |
The Other Direction
| Kilometers | Nautical Miles |
|---|---|
| 1 km | 0.539957 nmi |
| 2 km | 1.0799 nmi |
| 5 km | 2.6998 nmi |
| 10 km | 5.3996 nmi |
| 25 km | 13.4989 nmi |
| 50 km | 26.9978 nmi |
| 100 km | 53.9957 nmi |
| 500 km | 269.9784 nmi |
| 1,000 km | 539.9568 nmi |
What Each Unit Is
Nautical Miles (nmi) — exactly 1,852 metres. One minute of latitude along a meridian, which is why it is the unit of sea and air navigation.
Kilometers (km) — 1,000 metres. The metric system’s road-scale unit, adopted across most of the world in the 19th century.
A Sense of Scale
One knot is one nautical mile per hour- A nautical mile is about 15% longer than a statute mile
- A 20-minute walk covers about 1.5 km
- A marathon is 42.195 km
- A cruising airliner flies at 11 km
Doing It in Your Head
Multiply by 11, then divide by 6. That is off by 1.01% — close enough to judge a
distance, a weight or a price, and not close enough to sign off on a drawing.
Exact Mental shortcut 18.52 km 18.3333 km 185.2 km 183.3333 km
Precision
The factor 1.852 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.
Watch Out For
- A nautical mile is not a statute mile. Mixing them up understates a distance by roughly 15%.
In Code
`javascript
const nauticalMileToKilometer = (value) => value * 1.852;
``
Where This Conversion Comes Up
- Construction
- Navigation
- Sports
- Sewing
- Mapping
How Many Decimals Do You Need?
Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 nmi with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 nmi becomes | Error |
|---|---|---|---|
| 0 | 2 | 274 | 7.9914% |
| 1 | 1.9 | 260.3 | 2.5918% |
| 2 | 1.85 | 253.45 | 0.1080% |
| 3 | 1.852 | 253.724 | — |
| 4 | 1.852 | 253.724 | — |
The right number of significant figures is set by your input, not by the converter. If you measured nautical miles to three significant figures, the answer in kilometers is only good to three — writing more digits claims precision the measurement never had.