Running Pace Calculator
Turn a target finish time into an exact split-by-split plan.
Set your target
Pick a race distance or enter your own, then add the finish time you are aiming for.
Your pace
All values are derived from the distance and target time you entered.
Split-by-split plan
One row per km, with cumulative elapsed time.
| Segment (km) | Length | Half | Pace /km | Time | Elapsed |
|---|---|---|---|---|---|
| 1 | 1 | first | 5:00 | 5:00 | 5:00 |
| 2 | 1 | first | 5:00 | 5:00 | 10:00 |
| 3 | 1 | first | 5:00 | 5:00 | 15:00 |
| 4 | 1 | first | 5:00 | 5:00 | 20:00 |
| 5 | 1 | first | 5:00 | 5:00 | 25:00 |
| 6 | 1 | second | 5:00 | 5:00 | 30:00 |
| 7 | 1 | second | 5:00 | 5:00 | 35:00 |
| 8 | 1 | second | 5:00 | 5:00 | 40:00 |
| 9 | 1 | second | 5:00 | 5:00 | 45:00 |
| 10 | 1 | second | 5:00 | 5:00 | 50:00 |
Work backwards from a pace
Enter a pace to see the finish time for the same distance.
This calculation ignores terrain, elevation, weather and fatigue. Use it as a planning reference, not as a training prescription.
How this tool works
- 1 mile = 1.609344 km. Distances are split into whole units plus one final partial unit.
- Negative split: the first half runs the chosen percentage slower per unit than the second half.
- Both half paces are solved algebraically so every segment time sums to the exact target time.
- No allowance is made for terrain, elevation, weather or fatigue.
Read the full guides
The step-by-step guides behind this tool, from the Howcompass library.
Questions & answers
Do the split times add up exactly to my goal?
Yes. The first- and second-half paces are solved from one equation (T = u₁L₁ + u₂L₂), so the segment times sum to the target instead of drifting through rounding.
What is a negative split?
Running the second half faster than the first. Set a percentage (for example 3%) and the tool makes the first half that much slower per unit while keeping the total time unchanged.
Does it work for miles and marathons?
Yes. Choose km or miles and enter any distance. The table uses one row per unit, with a shorter final row for distances like 21.1 km.
Privacy & limits
Your target time stays in this browser tab. Nothing is uploaded.
This is a pacing calculation, not coaching or medical advice. Build training plans appropriate to your own fitness.
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