To convert kilometers to miles, multiply by 0.621371. So 5 km is 3.11 miles, 10 km is 6.21 miles and 100 km is 62.14 miles. To go from miles to kilometers, multiply by 1.609344. That second number is exact, because the mile is defined in meters.
Why is a mile exactly 1.609344 km? #
The international mile is 1,760 yards, and since 1959 the yard has been defined as exactly 0.9144 m. Multiply them and a mile is 1,609.344 m exactly, the figure listed as exact in NIST SP 811. So miles to km is exact, and km to miles (1 ÷ 1.609344 = 0.62137119…) is always rounded.
Until recently the US also had a slightly different “survey mile” for land surveying, based on the old survey foot. NIST retired the US survey foot on January 1, 2023. The difference was about 2 parts per million, around an eighth of an inch per mile, so it never mattered outside surveying.
What’s the quickest way to convert km to miles in your head? #
Three shortcuts, from roughest to best:
- Multiply by 0.6. 10 km becomes 6 miles. It runs about 3.4% low, so 100 km comes out as 60 miles instead of 62.1.
- Multiply by 5/8 (halve, halve, halve, then times 5). 40 km ÷ 8 = 5, × 5 = 25 miles. Exact answer: 24.85. It’s about 0.6% high.
- The Fibonacci trick. Consecutive Fibonacci numbers happen to be close to the mile/km ratio: 5 mi ≈ 8 km, 8 mi ≈ 13 km, 13 mi ≈ 21 km, 21 mi ≈ 34 km. So 13 km is about 8 miles (exact: 8.08).
For miles to km, multiply by 1.6 (add 60%). 50 miles becomes 50 + 30 = 80 km. The exact answer is 80.47, so it’s about 0.6% low.
Race distances in km and miles #
| Race | Kilometers | Miles |
|---|---|---|
| 1K | 1 | 0.62 |
| 5K | 5 | 3.11 |
| 8K | 8 | 4.97 |
| 10K | 10 | 6.21 |
| 15K | 15 | 9.32 |
| Half marathon | 21.0975 | 13.11 |
| 25K | 25 | 15.53 |
| 30K | 30 | 18.64 |
| Marathon | 42.195 | 26.22 |
| 50K ultra | 50 | 31.07 |
| 100K ultra | 100 | 62.14 |
The marathon’s 26.2 miles is the rounded version of 26.219. Enter 26.2 miles and convert, and you get 42.16 km, about 30 m short of a real marathon.
km to miles chart #
| km | miles | km | miles | |
|---|---|---|---|---|
| 1 | 0.621 | 30 | 18.641 | |
| 2 | 1.243 | 40 | 24.855 | |
| 3 | 1.864 | 50 | 31.069 | |
| 5 | 3.107 | 80 | 49.710 | |
| 8 | 4.971 | 100 | 62.137 | |
| 10 | 6.214 | 160 | 99.419 | |
| 15 | 9.321 | 200 | 124.274 | |
| 20 | 12.427 | 500 | 310.686 | |
| 25 | 15.534 | 1,000 | 621.371 |
Miles to km chart #
| miles | km | miles | km | |
|---|---|---|---|---|
| 0.25 | 0.402 | 20 | 32.187 | |
| 0.5 | 0.805 | 26.2 | 42.165 | |
| 1 | 1.609 | 30 | 48.280 | |
| 2 | 3.219 | 50 | 80.467 | |
| 3 | 4.828 | 60 | 96.561 | |
| 5 | 8.047 | 100 | 160.934 | |
| 10 | 16.093 | 500 | 804.672 | |
| 13.1 | 21.082 | 1,000 | 1,609.344 |
How do you convert running pace from km to miles? #
Pace works backwards from distance: a mile is longer, so pace per mile is a bigger number. Multiply minutes per km by 1.609344 to get minutes per mile, then turn the decimal into seconds (× 60).
| Pace per km | Pace per mile |
|---|---|
| 4:30 /km | about 7:15 /mi |
| 5:00 /km | about 8:03 /mi |
| 6:00 /km | about 9:39 /mi |
Worked through for 5:00/km: 5 × 1.609344 = 8.047 minutes, and 0.047 × 60 = 2.8 seconds, so 8:03 per mile. Going the other way, a 10:00/mi pace is 10 ÷ 1.609344 = 6.214 minutes, or about 6:13 per km.
What about nautical miles? #
A nautical mile is a different unit, used at sea and in aviation. It’s exactly 1,852 m, which makes it 1.852 km or about 1.151 statute miles. Speeds in nautical miles per hour are knots. If a boat trip is listed as 10 nautical miles, that’s 18.5 km, or 11.5 ordinary miles.
Converting km and miles on your phone #
Convert Units Calculator covers micrometers through kilometers, plus inches, feet, yards, miles and nautical miles, in its Length category. Type 26.2 with miles selected and it shows 42.164813 km with feet, meters and nautical miles worked out underneath, so a follow-up question is already answered. It uses the exact 1,609.344 m mile and works without a connection. For speeds rather than distances, use its Speed category, covered in mph to km/h.
For shorter lengths, see cm to inches. If you’re curious why road signs in one country say miles and in the next say kilometers, how the metric system works explains the metric side.
Frequently asked questions #
How many miles is a 5K? #
A 5K is 3.107 miles, usually rounded to 3.1 miles.
How many miles is 10 km? #
10 km is 6.214 miles, usually rounded to 6.2 miles.
How many km are in a mile? #
One mile is exactly 1.609344 km, a little over one and a half kilometers.
Is a kilometer longer than a mile? #
No. A kilometer is about 62% of a mile. It takes roughly 1.6 km to make one mile.
How many kilometers is a marathon? #
A marathon is 42.195 km, which is 26.219 miles. The familiar “26.2 miles” is the rounded version.