Convert kilometres to miles with the exact formula, worked examples, quick estimates, and the crucial difference between statute and nautical miles.
To convert kilometres to statute miles, multiply the kilometre value by 0.621371. For example, 100 km × 0.621371 = 62.1371 miles, normally rounded to 62.14 miles. For a quick estimate, multiply by 0.62. In aviation, check whether the distance should instead be expressed in nautical miles.
What is the kilometres-to-miles formula?
The exact conversion is kilometres divided by 1.609344; the practical multiplication is kilometres multiplied by approximately 0.621371192.
miles = kilometres ÷ 1.609344
miles = kilometres × 0.621371192
The international statute mile is defined as exactly 1.609344 kilometres. For general flight- and train-simulator use, “miles” here means statute miles unless the display is labelled NM. In a spreadsheet, if the kilometre value is in cell A1, use =A1/1.609344.
Keep several decimal places during the calculation and round only the final answer. Two decimal places are usually sufficient for map distances; retain more precision when adding multiple route legs.
Kilometres-to-miles conversion table
These common conversions use international statute miles and are rounded only for display.
| Kilometres | Miles |
|---|---|
| 1 km | 0.621371 mi |
| 5 km | 3.10686 mi |
| 10 km | 6.21371 mi |
| 25 km | 15.5343 mi |
| 50 km | 31.0686 mi |
| 100 km | 62.1371 mi |
| 250 km | 155.343 mi |
| 1,000 km | 621.371 mi |
How can I estimate kilometres in miles mentally?
Multiply by 0.62 for a quick estimate, or take five-eighths of the kilometre value when mental arithmetic is easier. Five-eighths equals 0.625, so it overestimates the correct result by about 0.6%.
For example, five-eighths of 80 km is 50 miles; the more accurate result is 49.71 miles. Use the shortcut for a quick range check, but use 0.621371192 when fuel, timing or accumulated distance depends on the result.
Do flight simulators use nautical miles instead?
Flight simulators generally use nautical miles for aeronautical route distances, GPS and FMS legs, and DME readouts. A nautical mile is exactly 1.852 kilometres, so convert kilometres to nautical miles by dividing by 1.852 or multiplying by approximately 0.539957.
This means 100 km is 62.14 statute miles but only 54.00 nautical miles. Our breakdown of aviation distance units explains why the two mile units differ. For flight-plan legs, use the separate method for calculating and tracking nautical miles across a route.
Train simulators and land maps normally use kilometres or statute miles according to the country represented. Always read the unit beside the number rather than assuming that every simulator uses the same kind of mile.
What mistakes cause incorrect conversions?
- Reversing the factor: multiplying kilometres by 1.609344 converts in the wrong direction. Because a mile is longer than a kilometre, the number of miles should be smaller than the number of kilometres.
- Confusing statute and nautical miles: never treat a statute-mile result as an NM value. The difference is roughly 15%.
- Rounding each route leg: add precise values first, then round the total. Repeated rounding can create a noticeable error across a long flight or railway route.
- Applying a linear factor to area: square kilometres require a different conversion. Multiply km² by approximately 0.386102 to obtain mi².
- Mixing speed units: the same 0.621371 factor converts km/h to mph because both are measured per hour. Knots are nautical miles per hour, so use the correct knots-to-mph calculation for cockpit speeds.
How do I convert miles back to kilometres?
Multiply statute miles by exactly 1.609344 to convert them back to kilometres. For example, 50 miles × 1.609344 = 80.4672 km. If the original miles value was rounded, the reversed result will also be approximate.