Running Pace Calculator
Plan your race strategy. Calculate pace, finish time, or distance instantly.
The Pace Formula
Pace is defined as the time it takes to cover a specific unit of distance. Conversely, Time = Pace × Distance.
Manual Calculation Example
Calculate the pace for a **10 km** run completed in **50 minutes**.
Common Race Distances
Here are the standard distances for popular road races. To turn a 5K, 10K or half-marathon result into a realistic marathon goal before setting a pace here, see how far the Riegel race time formula misses a marathon and the mileage-based correction.
How the calculator converts between pace, time and distance
Behind the screen everything is converted to seconds and kilometres. Miles are multiplied by 1.60934 and metres divided by 1,000. A pace per mile is divided by 1.60934 to become seconds per kilometre. The tool then solves one of three equations: pace = time / distance, time = distance x pace, or distance = time / pace. The answer is converted back to the unit you picked and rounded to the nearest second, or to two decimals for distance.
NIST defines the international mile as exactly 1.609344 km. The calculator's 1.60934 is short by four millionths of a kilometre per mile, which changes a marathon finish by a few hundredths of a second.
Second worked example: 10 miles at 9:30 per mile
Choose Time, enter 10 miles and a pace of 9:30 per mile. Pace in seconds is 9 x 60 + 30 = 570 s per mile, or 570 / 1.60934 = 354.2 s per km. Distance is 10 x 1.60934 = 16.0934 km. Time is 16.0934 x 354.2 = 5,700 s, which is 1:35:00.
The Quick Splits apply the same 354.2 s per km to fixed distances: 5 km takes 29:31, 10 km 59:02, a half marathon (21.0975 km) 2:04:32, and a marathon (42.195 km) 4:09:05. Those are the exact distances World Athletics uses for road races.
Splits after solving for pace
When you solve for pace, the pace boxes are greyed out and the Quick Splits take the pace the calculator has just worked out. Enter 50:00 for 10 km and the result is 5:00 per km, so the splits read 25:00 for 5 km, 50:00 for 10 km, 1:45:29 for the half and 3:30:59 for the marathon. In Time and Distance modes the splits use the pace you typed.
Times are rounded to the nearest whole second before they are split into hours, minutes and seconds. A computed 359.6 seconds therefore shows as 0:06:00. If you need tenths of a second for track splits, work them out by hand from the formula above.
Limits and edge cases
- Every result assumes a perfectly even pace; hills, wind, heat, crowds and fuel stops are not modelled.
- Splits for longer races repeat your current pace and are not fitness-based predictions.
- Pace per metre is so small that it displays as 00:00:00; use per km or per mile instead.
- A distance of zero returns 00:00:00 rather than an error.
- GPS distance can differ from a certified course, so watch pace and official pace may not match.
Disclaimer: Splits and finish times here are pure arithmetic and say nothing about whether your body can sustain that pace. Ramp up training gradually; a heart, lung or joint condition is a reason to talk to a doctor before racing efforts.
Sources checked
- NIST Guide to the SI, Appendix B.8: conversion factors: 1 mile = 1.609 344 km (exact) (checked 2026-10-22)
- World Athletics: Half marathon: 21.0975 km (checked 2026-10-22)
- World Athletics: Marathon: 42.195 km (checked 2026-10-22)
Frequently Asked Questions
How do I calculate my running pace?
What is a good 5K pace for beginners?
What pace do I need for a sub-4 hour marathon?
Are the Quick Splits a race prediction?
What mile-to-kilometre factor does the calculator use?
About the Pace Calculator
Determine your running pace or finish time for 5K, 10K, half, and full marathons. Perfect for race training and runner goal setting.