A running pace calculator for any distance
This pace calculator solves the three numbers every runner juggles: pace, finish time and distance. Give it any two and it works out the third, in kilometres or miles, with one-tap presets for the 5K, 10K, half marathon (21.0975 km) and marathon (42.195 km).
Alongside the answer you get pace per km and per mile, speed in km/h and mph, a split table for every kilometre or mile, and predicted times for other race distances using Riegel’s endurance formula. Use it to set a goal pace for race day, check how fast your last run really was, or plan a walking or cycling route. For a printable plan see the marathon pace chart; for a prediction with an adjustable exponent, the race time predictor; for belt settings, the treadmill pace calculator; and for a unit chart, the pace converter.
How to use the pace calculator
- Choose what to calculate: Pace, Finish time or Distance.
- Enter the distance in km or miles, or pick a race such as Half marathon from the list.
- Type your time in hours, minutes and seconds, and/or your pace in minutes and seconds per km or per mile.
- Read the answer at the top and the pace, speed and distance conversions below it.
- Check the predicted times for other races and use the split table as a pacing plan, for example on a pace band.
Pace Calculator features
Solve for anything
Calculates pace from distance and time, finish time from distance and pace, or distance from time and pace.
Race presets
5K, 10K, half marathon and marathon distances, accurate to the metre in both km and miles.
km and mile conversions
Every result shows pace per km and per mile plus speed in km/h and mph, so treadmill and watch settings match.
Split table
Elapsed time at every kilometre or mile, including the final part-split, for even pacing.
Race predictor
Estimates your time for the mile, 5K, 10K, half and full marathon from one performance.
Pace, speed and time formulas
Pace = time ÷ distance, usually written in minutes and seconds per kilometre or per mile. Speed = distance ÷ time, in km/h or mph. Time = pace × distance. One mile is exactly 1.609344 km, so a pace per mile is the pace per km multiplied by 1.609344.
Worked example: a 10K in 50:00 is 3,000 seconds ÷ 10 km = 300 seconds, or 5:00 per km. Multiply by 1.609344 to get 8:03 per mile. The speed is 10 km ÷ 0.8333 h = 12 km/h, or about 7.46 mph. To convert a speed to other units, use the speed converter.
| Pace per km | Per mile | 5K | 10K | Half marathon | Marathon |
|---|---|---|---|---|---|
| 4:00 | 6:26 | 20:00 | 40:00 | 1:24:23 | 2:48:47 |
| 5:00 | 8:03 | 25:00 | 50:00 | 1:45:29 | 3:30:59 |
| 6:00 | 9:39 | 30:00 | 1:00:00 | 2:06:35 | 4:13:10 |
| 7:00 | 11:16 | 35:00 | 1:10:00 | 2:27:41 | 4:55:22 |
Predicting race times with Riegel’s formula
In 1977 the engineer and marathoner Peter Riegel published a simple model for how pace slows as distance grows: T₂ = T₁ × (D₂ ÷ D₁)1.06. Doubling the distance takes slightly more than double the time because the exponent is above 1.
For example, a 10K in 50:00 predicts a half marathon in about 1:50:19 and a marathon in about 3:50:01. The formula works best for efforts lasting roughly 3½ minutes to 4 hours, and assumes you have trained properly for the longer race. Many recreational runners find marathon predictions optimistic unless they have built up their long runs, so add a margin for your first one.
Pacing tips for race day
- Start controlled. Even or slightly negative splits — a second half as fast as or faster than the first — are usually the quickest way to finish.
- Allow for conditions. Heat, humidity, hills and wind all slow you down. Adjust your goal pace instead of chasing it.
- Watch GPS drift. Watches often measure a race slightly long, so your watch pace may read a little faster than your official pace.
- Use heart rate too. Pair your pace targets with the heart rate zone calculator to keep easy runs easy.
- Fuel the long ones. For runs over about 90 minutes, plan fluids and carbohydrate; the calories burned calculator estimates how much energy a run uses.
Pace Calculator FAQ
How do I calculate my running pace?
Divide your time by the distance. If you ran 5 km in 27:30, that is 1,650 seconds ÷ 5 = 330 seconds, or 5:30 per km. Choose Pace in the calculator, enter the distance and time, and it shows your pace per km and per mile.
How do I convert pace per km to pace per mile?
Multiply the pace per km by 1.609344. A 5:00 /km pace is 8:03 /mile; a 6:00 /km pace is 9:39 /mile. To go the other way, divide the pace per mile by 1.609344.
What pace do I need for a sub-2-hour half marathon?
You need to average faster than 5:41 per km, or 9:09 per mile, for all 21.0975 km. Choose Finish time, pick Half marathon and try different paces to see the finish time each one gives.
How long is a half marathon and a marathon?
A half marathon is 21.0975 km (13.1 miles) and a marathon is 42.195 km (26.2 miles). The presets use these exact distances.
How accurate are the race time predictions?
They are a reasonable guide when you are equally trained for both distances, and the formula is widely used by coaches. Real results depend on training, course and weather, so treat predictions as estimates rather than guarantees.
Can I use the pace calculator for walking or cycling?
Yes. Pace and speed work the same way for any activity. Cyclists usually think in km/h or mph, which the calculator shows alongside pace.