Running Pace Calculator
Pace, time or distance from the other two, with splits.
Minutes and seconds (50:00), or hours, minutes and seconds (1:45:30). A single number is minutes.
Fill in the fields and the answer appears here.
The predictions assume you have trained for the distance — a marathon does not follow from a 5K pace without the long runs. An estimate, not a promise; and if you have a health condition, get checked before training for long races.
How this was worked out
Fill in the fields and the answer appears here.
Guide: Two numbers give the third2 min read
Two numbers give the third
Distance, time and pace are tied by one sum: pace = time ÷ distance. Knowing two gives the third. Choose what you want to find — the pace of a race you ran, the finish time of one you will run at a pace, or how far a time will take you — and type the other two. The 5K, 10K, half and marathon shortcuts fill in the official distance.
The answer gives the pace per kilometre and per mile, the speed, and a table of splits: what the clock should read at every kilometre or mile, to check yourself during the race. The table downloads as a CSV.
Predictions: Riegel’s formula
From a real effort, the calculator estimates your time at the classic distances with Peter Riegel’s formula (1981): time grows with distance to the power of 1.06, a little more than in proportion, because nobody holds 5K pace for a marathon. It was fitted on records from the mile to the marathon.
It is an estimate, and optimistic for long races when the training was not built for them. Use it to choose a starting pace, not as a promise.
Pace and heart rate
Pace and heart rate tell the same story from two sides. The heart rate zone calculator tells you which zone a pace puts you in. Everything here runs in your browser.
How we calculate
Riegel (1981)
time₂ = time₁ × (distance₂ ÷ distance₁)^1.06
Source: Riegel PS. Athletic records and human endurance. American Scientist. 1981;69(3):285-290.
Pace and speed
Pace = time ÷ distance; speed = distance ÷ time. 1 mile = 1.609344 km, exactly.
Frequently asked questions
How do I calculate my running pace?
Divide the time by the distance: 50 minutes for 10 km is 5:00 per kilometre. Choose “Find the pace”, type the distance and the time, and the calculator gives the pace in both units, the speed and every split.
What pace do I need for a sub-2-hour half marathon?
5:41 per kilometre, or 9:09 per mile, held for 21.0975 km. Choose “Find the pace”, pick Half marathon and type 2:00:00 — the table shows the time at every kilometre so you can check yourself during the race.
How do I convert min/km to min/mile?
Multiply by 1.609344, the kilometres in a mile: 5:00 per km is 8:03 per mile. Going the other way, divide. The calculator shows both whichever unit you choose.
How accurate are the race predictions?
They use Riegel's formula (1981), fitted on records from the mile to the marathon: time grows with distance to the power of 1.06. It predicts short races well and is optimistic for long ones unless your training was built for them — a marathon needs the long runs a 10K does not.
How do I type the time?
As minutes and seconds (50:00) or hours, minutes and seconds (1:45:30). A single number is read as minutes.