Convert kilometres to miles
Turn any distance from kilometres into statute miles using the official factor.
Calculator inputs
Results
Enter your values and press “Calculate” to see the result.
In short
- What it calculates
- Turn any distance from kilometres into statute miles using the official factor.
- Formula used
miles = kilometres ÷ 1.609344- Example
- 100 km to miles:
Kilometres to miles converter
The statute mile is used in the United States and the United Kingdom, so this conversion comes up constantly when reading travel distances, race lengths or vehicle specifications.
How it works
The distance in kilometres is divided by 1.609344, the exact number of kilometres in an international mile since 1959.
Formula
miles = kilometres ÷ 1.609344
1 mi = 1.609344 km exactly
1 km = 0.621371 mi
Worked example
100 km to miles:
100 ÷ 1.609344 = 62.137 miles
A marathon of 42.195 km is 26.219 miles.
Explanation
The 1.609344 factor is exact by agreement
It is not an approximation. In 1959 the English-speaking countries signed the international yard and pound agreement, fixing the yard at exactly 0.9144 metres. From that come the 1,609.344-metre mile and the 25.4-millimetre inch, with no hidden decimals.
Where miles are still used
The United States, the United Kingdom, Liberia and Myanmar keep miles on road signs. The British case is the oddest: distances and speed limits are in miles, but petrol is sold in litres and food in grams. The same journey is measured in miles and fuelled in litres.
The Fibonacci trick
Consecutive Fibonacci numbers approximate the conversion: 5 km is about 3 miles, 8 km about 5, 13 km about 8, 21 km about 13. It is no coincidence, because the ratio between consecutive terms tends to the golden ratio, 1.618, very close to the real 1.609.
Distances worth memorising
A marathon is 42.195 km, that is 26.2 miles. A half marathon, 21.1 km or 13.1 miles. The 100 km/h of a European motorway is 62 mph, and the British 70 mph is 113 km/h.
Frequently asked questions
Is a mile the same as a nautical mile?
No. A nautical mile is 1,852 metres and is used in sea and air navigation; the statute mile is 1,609.344 metres.
How do I do it in my head?
Multiply by 6 and divide by 10: 100 km ≈ 60 miles. The error is around 3%.
Why does the UK use miles and litres at once?
Because metrication was left half finished: trade and packaging went metric, but road signage stayed in miles and yards.
How many miles is a marathon?
26.2 miles, equivalent to the official distance of 42.195 kilometres.
Need to calculate something else?
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