How to use
Enter a distance and a time to see your pace (minutes per mile or kilometer) and average speed, plus predicted times for standard race distances. Enter time as h:mm:ss or mm:ss, e.g. 25:00 or 1:52:00.
Use “Find” for the other questions: your finish time at a given pace (say, a marathon at 8:00 per mile) or how far you’ll go in a given time. For standard races — 5K, 10K, half marathon, marathon — just pick the race instead of typing the distance. The splits table shows the elapsed time at every mile (or kilometer) at an even pace.
How it’s calculated
- Pace = time / distance: a 5K in 25:00 is 8:03 per mile.
- Speed = distance / time: that’s about 7.5 mph.
- Predictions use Peter Riegel’s formula:
T₂ = T₁ × (D₂ / D₁)^1.06— the longer the race, the more your pace slows.
Example
5K in 25:00 → 8:03 min/mi. Predicted: 10K 52:07, half marathon 1:55:00, marathon 3:59:47.
FAQ
How accurate is the marathon prediction? It’s a guide for runners who train for long distances. Without enough mileage, real marathon times are usually noticeably slower.
What’s a good running pace? It depends on age, experience and goals. Easy runs are usually done at a conversational pace.
Can I use kilometers? Yes — switch units to metric to see pace per kilometer.
To estimate how many calories you need with training, try the calorie calculator.