About the Running Pace Calculator
Pace is how long it takes you to cover one mile (or one kilometer) – the number most runners track on their watch. Run 3 miles in 27 minutes and your pace is 9:00 per mile, which equals a speed of 6.7 mph.
This calculator works both ways: from distance and time to pace and speed, or from a target pace to finish times for every common race distance. It also builds an even-pace split table and predicts your times at other distances with Peter Riegel's formula. Switch between miles and kilometers at any time.
How to use
- Pick a mode at the top (distance + time → pace, or pace → finish times) and choose miles or km.
- Type a distance or tap 5K, 10K, Half or Marathon, then enter your time in the hours, minutes and seconds boxes.
- Read your average pace and speed, the race time predictions and the split table.
- Planning a goal race? Switch to “Pace → finish times” and try different paces to see the finish time each one gives you.
Pace and speed formulas
- Pace (min/mile) = time (minutes) ÷ distance (miles) – e.g. 27 min ÷ 3 mi = 9:00/mi
- Speed (mph) = 60 ÷ pace in minutes – e.g. 60 ÷ 9 = 6.7 mph
- Finish time = pace × distance – e.g. 8:00/mi × 26.2188 mi ≈ 3:29:45
- 1 mile = 1.609344 km, so pace per km = pace per mile ÷ 1.609344
A marathon is 26.2188 miles (42.195 km) and a half marathon is 13.1094 miles (21.0975 km). Results are rounded to the nearest second.
Pace chart: finish times by pace
| Pace | Speed | 5K | 10K | Half | Marathon |
|---|---|---|---|---|---|
| 7:00/mi | 8.6 mph | 21:45 | 43:30 | 1:31:46 | 3:03:32 |
| 8:00/mi | 7.5 mph | 24:51 | 49:43 | 1:44:53 | 3:29:45 |
| 9:00/mi | 6.7 mph | 27:58 | 55:55 | 1:57:59 | 3:55:58 |
| 10:00/mi | 6.0 mph | 31:04 | 1:02:08 | 2:11:06 | 4:22:11 |
| 11:00/mi | 5.5 mph | 34:11 | 1:08:21 | 2:24:12 | 4:48:24 |
| 12:00/mi | 5.0 mph | 37:17 | 1:14:34 | 2:37:19 | 5:14:38 |
A sub-4-hour marathon needs an average of about 9:09 per mile; breaking 3 hours takes about 6:52 per mile.
Predicting race times with the Riegel formula
In 1977 engineer and marathoner Peter Riegel proposed a simple way to estimate a time at one distance from a result at another:
T₂ = T₁ × (D₂ ÷ D₁)1.06
Example: a 10K in 50:00 → marathon = 3,000 s × 4.21951.06 ≈ 13,801 s ≈ 3:50:01. The exponent 1.06 captures how pace slows as distance grows.
Limitations: the formula was fitted to efforts between roughly 3.5 minutes and 4 hours and assumes you are equally trained for both distances. Predicting a marathon from a 5K or 10K is usually optimistic unless your weekly mileage and long runs are marathon-ready. Heat, hills and fueling are not included, so treat it as a starting point for goal setting.
FAQ
How do I calculate my pace per mile?
Convert your time to minutes and divide by the distance in miles. 5 miles in 47:30 is 47.5 ÷ 5 = 9.5 minutes, i.e. 9:30 per mile (0.5 minutes = 30 seconds).
How do I convert pace to mph for a treadmill?
Speed in mph = 60 ÷ pace in minutes per mile. A 10:00 mile is 6.0 mph, an 8:00 mile is 7.5 mph, a 6:00 mile is 10 mph.
What pace do I need for a sub-4-hour marathon?
4 hours is 240 minutes; 240 ÷ 26.2188 ≈ 9.15 minutes, so about 9:09 per mile (5:41 per km). Many runners aim a few seconds faster to allow for water stops and late-race fatigue.
What is the last row in the split table?
When the distance is not a whole number of miles or kilometers, the last row is the short remaining segment – for a marathon in miles, the final 0.2188 mile after mile 26 – together with your finish time.
Why might my real race differ from the Riegel prediction?
The formula assumes similar fitness at every distance. Endurance, training volume, weather and course profile all matter, and predictions from short races to the marathon tend to be too fast.