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Running Pace Calculator

Calculate pace, time or distance for any run - all in your browser.

How Running Pace Calculator works

Running pace connects three variables: distance (km), total time (H:MM:SS format) and pace (M:SS per kilometre). Enter any two and this tool instantly derives the third using the relationship: total time in seconds equals distance multiplied by pace in seconds per kilometre. Results display in both min/km and min/mi simultaneously, so there is no separate unit conversion step.

Pace is rounded to the nearest second in M:SS format, matching the way race plans and training schedules are written. All arithmetic runs locally in your browser; nothing is uploaded to any server.

Written by Bastien Sulyan

How to use Running Pace Calculator, step by step

  1. Enter any two of the three fields: distance in km, total time in H:MM:SS format, or pace in M:SS per km.
  2. Leave the third field blank or clear it.
  3. Click Calculate (or the result updates automatically when you tab between fields).
  4. Read the derived value and the pace shown in both min/km and min/mi.
  5. Adjust either known value to explore different race or training scenarios.

Common use cases

  • Working out the finish time for a 10 km race when you plan to run at 5:30 per km.
  • Calculating the average pace you need to run a half marathon in under 2 hours (distance 21.0975 km, time 1:59:59).
  • Checking what average pace you actually ran after a training session by entering the GPS distance and your elapsed time.
  • Planning a tempo run by entering a target 5 km time to find the per-km pace you need to hold.

Frequently asked questions

Does this pace calculator upload any data?

No. All calculations run locally in your browser using plain JavaScript arithmetic. Nothing is sent to a server and the tool works fully offline after the page has loaded.

What formula is used?

Total time (seconds) = distance (km) times pace (seconds per km). Given distance and pace, time = distance times pace. Given time and distance, pace = time divided by distance. Given time and pace, distance = time divided by pace. The tool solves for whichever field is left empty.

How is the pace in min/mi calculated?

One mile equals approximately 1.60934 km. The pace in seconds per mile = pace in seconds per km times 1.60934. The result is then formatted as M:SS. Example: a 5:00 per km pace equals 5 times 60 = 300 seconds per km, times 1.60934 = 482.8 seconds per mile, which is 8:03 per mile.

What format should I use for time and pace?

Total time uses H:MM:SS (hours, minutes, seconds). Examples: 0:45:30 for 45 minutes 30 seconds, or 1:02:15 for 1 hour 2 minutes 15 seconds. Pace uses M:SS (minutes and seconds per km). Examples: 5:00 for exactly 5 minutes per km, or 4:30 for 4 minutes 30 seconds per km.

How accurate is it?

The calculation is exact to floating-point precision. Pace is displayed to the nearest second (M:SS) and distance is shown to three decimal places. For most running purposes these rounding levels match the precision of consumer GPS watches.

What is a good pace for a 5 km or 10 km race?

Pace depends entirely on fitness level and goals. As a rough guide: sub-20 minute 5 km requires a pace of 4:00 per km or faster; sub-25 minutes is 5:00 per km; sub-30 minutes is 6:00 per km. For a 10 km race, doubling those paces gives approximate finish times. Use this tool to find the exact pace for any target time.

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