The number to remember
1 mile = 1.60934 kilometres
That is the exact conversion. In practice, 1.609 is enough for road trips, and 1.6 is enough for a rough guess in your head. The reverse is just as useful: 1 kilometre = 0.62137 miles, roughly 0.62.
Why does this matter? Because the world is split. Britain and America measure roads in miles; almost everywhere else uses kilometres. A hire car abroad, a marathon training plan, a flight distance, a cycling app — sooner or later the units disagree, and a wrong conversion means a wrong arrival time or a wrong pace.
The formula
Kilometres = Miles × 1.60934
Miles = Kilometres × 0.62137
Worked example: a road trip of 180 miles. 180 × 1.60934 = 289.7 kilometres. Call it 290 km. The reverse: a 42-kilometre marathon in miles is 42 × 0.62137 = 26.1 miles — which is why a marathon is famously 26.2 miles.
A mental shortcut for the road
Multiplying by 1.609 in your head is awkward, so use the Fibonacci trick: take the miles, and the next number in the Fibonacci sequence is roughly the kilometres. 5 miles ≈ 8 km, 8 miles ≈ 13 km, 13 miles ≈ 21 km, 21 miles ≈ 34 km. It works because the ratio between consecutive Fibonacci numbers is close to 1.609. It is not exact, but for estimating a journey it is brilliantly fast.
An even simpler rule: multiply miles by 1.6. 100 miles × 1.6 = 160 km (exact: 160.9). You will be within 1% — good enough for any plan that is not a scientific measurement.
Quick conversion table
| Miles | Kilometres |
|---|---|
| 1 | 1.61 |
| 5 | 8.05 |
| 10 | 16.09 |
| 25 | 40.23 |
| 50 | 80.47 |
| 100 | 160.93 |
| 200 | 321.87 |
| 500 | 804.67 |
And the reverse:
| Kilometres | Miles |
|---|---|
| 1 | 0.62 |
| 10 | 6.21 |
| 50 | 31.07 |
| 100 | 62.14 |
| 250 | 155.34 |
| 500 | 310.69 |
Common mistakes
Using 1.5 instead of 1.6. It feels close, but on a 300-mile journey it underestimates by 27 km — enough to miss a fuel stop.
Converting speed the wrong way round. Speed limits convert with the same factor: 70 mph × 1.609 = 112.7 km/h. But remember that a speedometer showing km/h in a mph country needs the reverse — divide, do not multiply.
Confusing miles with nautical miles. A nautical mile is 1.852 km, used at sea and in aviation. If a flight distance looks oddly long, check whether it is nautical miles before you redo the maths.
Rounding too early. Convert first, round last. Rounding 1.60934 to 1.6 at the start is fine; rounding every intermediate step is how a 290 km trip becomes 284 km on paper.
Questions people actually ask
Is a mile longer than a kilometre?
Yes — one mile is about 1.6 kilometres. That is why mile numbers always look smaller than the same distance in kilometres.
Why do America and Britain still use miles?
History and habit. Both countries built their road systems in miles before metrication, and changing every road sign is expensive and unpopular. Most of the rest of the world switched to kilometres decades ago.
What is a 5K run in miles?
5 km × 0.62137 = 3.11 miles. A 10K is 6.21 miles, and a half marathon (21.1 km) is 13.1 miles.
Does my car’s odometer switch units?
Most modern cars let you switch the display between miles and kilometres in the settings menu. On a hire car abroad, check this before you drive — reading 100 on a km/h speedometer as if it were mph is a speeding fine waiting to happen.