Running Pace Calculator
Enter two of distance, pace and finish time to find the third. A table of split times at a steady pace is shown as well.
Formulas
- Finish time = pace (time per km) × distance (km)
- Pace = finish time ÷ distance (km)
- Distance = finish time ÷ pace
- Speed (km/h) = 3,600 seconds ÷ pace (seconds per km)
The calculation uses exact fractions. Miles are converted with 1 mile = 1,609.344 m.
Race distances
- Marathon = 42.195 km. The World Athletics Technical Rules (2026 edition), Rule TR55 (Road Races), list the standard distances and give "Marathon (42.195km)".
- Half marathon = 21.0975 km, exactly half of a marathon. The World Athletics page on the half marathon says it is "exactly half the length of a marathon, at 13.1094 miles or 21.0975km".
- 5 km, 10 km and the other road distances also appear in the rules as standard distances. TR55 also says that the length of a course shall not be less than the official distance for the event, and that at World Rankings Competitions the uncertainty in the measurement shall not exceed 0.1% (42 m for a marathon). Because of this, an actual course can be slightly longer than the nominal distance.
- 1 mile = 1,609.344 m (the road mile distance given in the same rule).
Examples
- 5 km at 5:00 per km → 25:00
- 10 km at 5:00 per km → 50:00
- Half marathon (21.0975 km) at 5:00 per km → 1:45:29.25 (1:45:29 to the second)
- Marathon (42.195 km) at 5:00 per km → 3:30:58.5 (3:30:59 to the second)
- Marathon in 3 hours 30 minutes → pace about 4:58.6 per km (298.61 seconds per km, speed about 12.06 km/h)
- Marathon in 4 hours (sub-4) → pace about 5:41.3 per km
- One hour at 5:00 per km → 12 km
Notes
- This calculator does not predict race times. It does not include formulas that predict a time for one distance from a time for another (such as Riegel's formula). The split table is a simple calculation for running at a constant pace.
- The ranges are: distance from 0.001 km to 1,000 km, pace from 1 second per km up to less than 100 minutes per km, and finish time under 1,000 hours. Minutes and seconds are entered as 0–59.
- To convert speeds between units, use the Speed Converter; for any other trip, the Speed, Distance & Time Calculator; and for lengths of time, the Time Converter or the Time Calculator.
Sources
- World Athletics, Competition and Technical Rules, 2026 Edition (Technical Rule TR55, Road Races; checked on October 31, 2026).
- World Athletics, Half marathon (checked on October 31, 2026).
Frequently asked questions
What pace do I need to run a marathon in 4 hours?
About 5:41 per km (5:41.3). Choose the marathon distance, enter 4 hours as the finish time, and select "Find pace".
What is 5:00 per km in miles per hour?
12 km/h (3,600 ÷ 300), which is about 7.46 miles per hour.
How do I turn a pace per km into a pace per mile?
Multiply the time per km by 1.609344. 5:00 per km is about 8:03 per mile.