How to use
- Choose what to calculate — pace, finish time or distance — and whether you think in miles or kilometers.
- Fill in the other two values. Times can be
1:45:30(h:mm:ss) or45:30(mm:ss); a single number is read as minutes. Pace is minutes:seconds per mile or km, such as8:30. - Tap 5K, 10K, Half or Marathon to drop in a race distance. You’ll see pace per mile and per km, speed, projected race times at that pace and a split table.
This calculator provides general information only. It is not medical advice or an exercise prescription.
Formulas
| To find | Formula |
|---|---|
| Pace | time ÷ distance |
| Finish time | pace × distance |
| Distance | time ÷ pace |
| Speed (mph) | 3,600 ÷ pace per mile in seconds |
| Race | Miles | Kilometers |
|---|---|---|
| 5K | 3.107 | 5 |
| 10K | 6.214 | 10 |
| Half marathon | 13.109 | 21.0975 |
| Marathon | 26.219 | 42.195 |
A mile is exactly 1.609344 km. The 42.195 km marathon distance comes from the 1908 London Olympic course and was made official by the IAAF (now World Athletics) in 1921.
Examples
- A 4-hour marathon needs 9:09 per mile (5:41/km); a 3-hour marathon needs 6:52 per mile (4:16/km).
- At 10:00 per mile: 5K in 31:04, 10K in 1:02:08, half in 2:11:06 and marathon in 4:22:11.
- 10 km in 55 minutes is 5:30/km, or 8:51 per mile.
- Running 30 minutes at 6:00/km covers 5 km.
Things to keep in mind
- Results assume an even pace the whole way. Hills, wind, aid stations and fatigue usually slow the second half of a race.
- Projected race times simply extend your current pace, so for longer distances they tend to be faster than what most runners actually achieve.
- GPS watches often read a little long because of corners and signal noise, and certified courses are measured along the shortest possible line with a 0.1% safety margin — so your watch will usually show more than 26.2 miles.
- Pushing an unrealistic goal pace raises injury risk. If you have a heart condition or other health concern, ask your doctor what intensity is safe.
FAQ
What is the difference between pace and speed?
Pace is the time it takes to cover one mile or kilometer; speed is the distance covered in an hour. Runners usually talk in pace, cyclists in speed.
How do I convert pace per mile to pace per km?
Switch the distance unit and the pace you entered converts automatically. By hand, divide your mile pace by 1.609344. For other distance conversions, use the length converter.
How much should I drink around a run?
Add your exercise minutes to the water intake calculator to include an allowance for training.