Pace Calculator
Running pace, finish time or distance, with race predictions and splits.
How to use Pace Calculator
- Choose what to calculate: pace, time or distance.
- Enter the other two. Pick a race distance or type your own; times are written h:mm:ss or mm:ss.
- Read the result, the pace in both units, your speed, race times at that pace and even splits.
How it works
Pace = time ÷ distance, time = pace × distance, distance = time ÷ pace. Pace per mile is pace per kilometre × 1.609344 (the exact length of a mile in kilometres), and speed in km/h is 60 ÷ pace in minutes per kilometre.
Race distances are the official ones: half marathon 21.0975 km and marathon 42.195 km. "Race times at this pace" simply multiplies the pace by each distance; it is not a fitness prediction, because nobody holds 5K pace for a marathon. Splits are even splits: the clock time at each kilometre or mile if you run a steady pace.
Example
10 km in 50:00 is a pace of 5:00 per km (8:03 per mile) and a speed of 12 km/h. Held for a marathon, that pace finishes in 3:30:59.
Frequently asked questions
What pace do I need for a sub-2-hour half marathon?
Choose "Pace", pick Half marathon and enter 2:00:00: you need 5:41 per km or 9:09 per mile. Aim a few seconds faster to allow for crowds and corners.
How do I convert pace per km to pace per mile?
Multiply by 1.609344. A 5:00 per km pace is 8:03 per mile. Both are shown for every result.
How do I enter the time?
As hours:minutes:seconds (1:45:30) or minutes:seconds (25:30). A single number is read as minutes.
Does this predict my race time from another distance?
No. It shows what a steady pace would give at each distance. Predicting performance across distances needs a fatigue model and depends heavily on training.
Can I use it for cycling, swimming or walking?
Yes. The arithmetic is the same; use metres for swimming distances.
Limitations
- Even pace only: hills, heat and fatigue are not modelled.
- Not a race-time predictor between distances.
Last reviewed November 9, 2026. How we build and test tools.