Pace Calculator
Choose what you want to find: pace from a distance and time, finish time from a distance and pace, or distance from a time and pace. Results show pace per mile and per kilometer, speed and race projections.
Last updated November 2, 2026
Result
Pace: 8:00 per mi
| Measure | Value |
|---|---|
| Distance | 5 miles |
| Time | 40:00 |
| Pace per mile | 8:00 |
| Pace per km | 4:58 |
| Speed | 7.5 mph (12.07 km/h) |
| Race | Finish time |
|---|---|
| 5K | 24:51 |
| 10K | 49:43 |
| Half marathon | 1:44:53 |
| Marathon | 3:29:45 |
Race times assume you hold the same pace for the whole distance, which is harder over longer races.
Show the work
Formula: Pace = time ÷ distance
- You entered 5 miles in 0 h 40 min 0 s = 2,400 seconds.
- Pace = time ÷ distance = 2,400 ÷ 5 = 480 seconds per mi = 8:00 per mi.
- Pace per mile 8:00 and per km 4:58 (1 mile = 1.609344 km).
- Speed = 3600 ÷ seconds per mile = 7.5 mph, or 12.07 km/h.
Result: Pace: 8:00 per mi
How pace is calculated
pace = time ÷ distance
time = distance × pace
distance = time ÷ pace
Pace is the time it takes to cover one unit of distance. Running 5 miles in 40 minutes is 2,400 seconds ÷ 5 = 480 seconds, or 8:00 per mile. Pace per kilometer is the pace per mile divided by 1.609344, so 8:00 per mile is 4:58 per km. Speed is 3,600 seconds divided by the pace in seconds: 7.5 mph at 8:00 per mile.
Race projections multiply your pace by the race distance (5K = 5 km, half marathon = 21.0975 km, marathon = 42.195 km). They assume you hold the same pace the whole way, which is harder as distance grows, so real long-race times are usually slower.
See how we calculate for the formulas, sources and review schedule behind every calculator.
This is an estimate, not medical advice
This calculator is a general training aid. It does not assess fitness or readiness for any distance, and it has not been reviewed by a medical professional. Build up distance gradually and talk to a doctor before starting a new exercise program if you have a health condition.
Sources
Official and primary sources for the statements on this page. Their authors have not reviewed or endorsed this page.
- National Institute of Standards and Technology, NIST Guide to the SI, Appendix B.8: Factors for Units Listed Alphabetically (web page, checked November 2, 2026). Lists the mile as exactly 1.609344 kilometers, the factor used to switch between pace per mile and pace per kilometer
Pace is time divided by distance, plain arithmetic with no medical source involved.
How to use the Pace Calculator
- Choose what to calculate and the unit (miles or kilometers).
- Enter the values for the other two measures.
- Read the pace, time or distance with speed and race projections, then use Copy, Print or Share.
Worked example
Running 5 miles in 40:00 is a pace of 8:00 per mile (4:58 per km, 7.5 mph). Holding that pace gives these projected finish times.
| Race | Finish time |
|---|---|
| 5K | 24:51 |
| 10K | 49:43 |
| Half marathon | 1:44:53 |
| Marathon | 3:29:45 |
Frequently asked questions
How do I calculate running pace?
Divide your total time by the distance. Enter both and choose Pace.
How do I convert pace per mile to per kilometer?
Divide the pace per mile by 1.609344. 8:00 per mile is about 4:58 per km.
Can I predict my marathon time from my 5K pace?
Only roughly. Most runners slow down over longer distances, so the projections here are best-case.
Can I enter seconds with decimals?
Yes. Seconds can include decimals, for example 30.5.
Are my numbers stored or sent anywhere?
No. The calculation runs in your browser and nothing you enter is saved or uploaded.