Running Pace Calculator
Solve the running pace triangle: enter any two of distance, time and pace to calculate the third. Shows pace per km and per mile, speed, a Riegel equivalent race-time predictor (5K, 10K, half, marathon and more) and an even-split table.
Input
Pick what to solve for; supply the other two values below.
Unit for a custom distance and for the calculated-distance result.
Total time as hh:mm:ss, mm:ss, or a number of minutes.
Distance between rows in the even-split table.
Output
| Metric | Value |
|---|---|
| No data yet | |
| Distance | Predicted Time | Pace /km | Pace /mile |
|---|---|---|---|
| No data yet | |||
| Split | Split Time | Cumulative |
|---|---|---|
| No data yet | ||
Guides
The Running Pace Calculator solves the classic pace triangle. Distance, time and pace are three sides of the same relationship — pace = time ÷ distance — so if you know any two, the third is fixed. Pick what you want to calculate, enter the other two values, and the tool works out the rest instantly, in your browser.
What it calculates
- Pace — enter a distance and a finish time to get your pace, shown both per kilometer and per mile.
- Time — enter a distance and a target pace to predict your finish time.
- Distance — enter a pace and a duration to find out how far you would run.
Every result also reports your speed in km/h and mph, so you can cross-check against a treadmill or GPS watch.
How to use it
- Choose what to calculate (pace, time, or distance).
- Fill in the two known values. Distance accepts a preset (1 mile, 5K, 10K, 15K, half marathon, marathon, 50K, 100K) or a custom value in km, miles or meters.
- Enter times as
hh:mm:ssormm:ss(for example1:45:30or50:00), and pace asmm:ssper km or per mile. - Read the result table, the equivalent race times and the split table below it.
Equivalent race times (Riegel formula)
Beyond the core answer, the tool predicts your times at other common race distances using Riegel's endurance formula:
T2 = T1 × (D2 ÷ D1) ^ 1.06
T1/D1 are your known time and distance; the 1.06 exponent models how pace slows as distance grows. This is a well-established way to translate a recent 5K or 10K into a realistic half-marathon or marathon goal. Predictions are most reliable within roughly a fourfold range of your known result and assume consistent training — they drift optimistic for very long extrapolations such as 5K to 100K.
Even-split table
The split table lists the time for each kilometer or mile at an even effort, plus the running cumulative total — a simple pacing sheet you can glance at during a race to check whether you are on schedule.
What is a good running pace?
There is no single answer; it depends on fitness, distance and terrain. A common recreational 5K pace is around 6:00–7:00 min/km (about 9:40–11:15 min/mile), while a sub-4-hour marathon needs roughly 5:41 min/km (9:09 min/mile) held for the full 42.195 km. Use the equivalent-times table to set a goal that matches your current fitness rather than guessing.
Does the calculator store my data?
No. All calculations run entirely in your browser — nothing you enter is uploaded or saved.