Enter any two of time, distance, and pace, and this calculator solves for the third. Switch the mode to choose what you want to find — your pace from a finished run, the finish time for a target distance and pace, or how far you'd go at a given pace and time. It also shows your speed and finish times for common race distances.
How to use each mode
- Calculate Pace: enter a completed time and distance. Use this after a run, walk, ride, swim, or row to find average pace and speed.
- Calculate Time: enter a distance and target pace to estimate a finish time. This assumes the same average pace from start to finish.
- Calculate Distance: enter elapsed time and average pace to find how far the effort covers.
Choose the distance and pace units independently. The calculator converts through metres and seconds, so a pace entered per mile can still be applied to a distance entered in kilometres.
Average pace versus split pace
The result is an average over the whole distance. Real efforts rarely have identical splits: hills, turns, aid stations, traffic, wind, heat, and fatigue can all change the pace from one segment to the next. If the goal is a specific finish time, divide the course into shorter checkpoints and use the average as a starting target rather than a promise of even splits.
For energy-use estimates, pass the activity duration and intensity to the Calories Burned Calculator. Pace alone does not measure exertion equally across terrain or people.
Common race distances
| Race | Distance |
|---|---|
| 5K | 5 km (3.11 mi) |
| 10K | 10 km (6.21 mi) |
| Half Marathon | 21.0975 km (13.11 mi) |
| Marathon | 42.195 km (26.22 mi) |
Examples
Pace from a 10 km run in 50:00
3,000 seconds ÷ 10 km = 300 s/km = 5:00 per kilometer (about 8:03 per mile, or 12.0 km/h). At that pace a marathon would take about 3:30:59.
Finish time for a half marathon at 5:00/km
21.0975 km × 300 s/km = 6,329 seconds = 1:45:29.
Formula
The three quantities are linked by one relationship:
pace = time ÷ distance
time = pace × distance
distance = time ÷ pace
Internally every value is converted to seconds and metres, the missing quantity is solved, then formatted back into your chosen units. The calculator uses the NIST conversion 1 mile = 1,609.344 metres and 1 yard = 0.9144 metre.
Using predictions responsibly
A pace-based race prediction assumes you can sustain the selected pace for the entire new distance. It does not adjust for fatigue as distance increases, course elevation, weather, surface, stops, or drafting. Predicting a marathon directly from a short fast effort can therefore be overly optimistic.
The common-distance table uses established race lengths. World Athletics lists 5 km, 10 km, half marathon, and marathon (42.195 km) among standard road race distances. Always use the organizer's measured course distance for an event plan.