Running Pace Calculator

Enter two of distance, time and pace to get the third and your speed, plus split tables, a goal-time pace chart and treadmill speed conversion. Use it to find the pace you need for a 5K, 10K, half marathon or marathon goal.

How to use

1. On the "Pace" tab, choose what to "Calculate", pick a distance (5K, 10K, half marathon, marathon or "Other") and enter a time or a pace.
2. Type times like 1:23:45 or 83:45 and paces like 5:30 or 5'30". "Estimated times at other distances" appear below.
3. On the "Splits" tab, choose "Split every" and the "Pacing" (even pace or negative split) to see the time for each split.
4. Use the "Pace chart" tab to print a range of goal times, and the "Treadmill" tab to convert speed and pace.

How it works

• Pace = time ÷ distance. Speed (km/h) = 60 ÷ pace in minutes per km. Time = pace × distance.
• 1 mile = 1.609344 km, a half marathon is 21.0975 km and a marathon 42.195 km.
• Estimated times use the Riegel formula, T2 = T1 × (D2 ÷ D1)^1.06 (1981). They are less reliable far from the distance you entered and are not a guarantee.

Questions and answers

What pace do I need for a 4-hour marathon?

4 hours ÷ 42.195 km is about 5:41 per km, or about 9:09 per mile. A 2-hour half marathon needs the same pace.

What is the pace for a 50-minute 10K?

50 minutes ÷ 10 km is 5:00 per km, which is a speed of 12 km/h.

How do I convert treadmill speed to pace?

Divide 60 by the speed. 10 km/h is 60 ÷ 10 = 6:00 per km; the other way, a 5:30 pace is 60 ÷ 5.5 ≈ 10.9 km/h.

Can I predict my marathon time from a 10K?

The Riegel formula gives an estimate. A 50-minute 10K suggests about 3 hours 50 minutes, but predictions from short races to the marathon are the least reliable.