| Split | Per split | Cumulative |
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Predictions assume an even (steady) pace. Real races vary with fatigue, hills and conditions, so use the result as a target to pace against.
How pace, time and distance fit together
The three are linked by one simple relationship: pace = time ÷ distance. Rearranged, time = pace × distance and distance = time ÷ pace. That is why you only ever need two of them — give the calculator any two and it solves for the missing one. The most recently edited two fields are treated as your inputs, and the third is filled in automatically, so you can flip between "what pace do I need?" and "how long will this take?" without clearing anything.
Pace versus speed
Pace and speed describe the same thing from opposite directions. Pace is time per distance (minutes per kilometre or mile) and gets a bigger number as you slow down; speed is distance per time (km/h or mph) and gets a bigger number as you speed up. Runners usually think in pace because it maps directly onto a watch during a run, while treadmills and cyclists tend to show speed. The calculator gives you both at once so you can move between the two worlds.
Kilometres, miles and race predictions
A mile is 1.609 kilometres, so a per-mile pace is always a larger number than the same effort in per-kilometre terms — 5:00 /km is about 8:03 /mi. Use the toggle to switch units without changing your effort. To predict a race, enter your goal pace and a race distance: the classic 5K, 10K, half marathon (21.0975 km) and marathon (42.195 km) presets are one tap away. Pair this with the Calories Burned Calculator to estimate a session's energy cost, or the Target Heart Rate Calculator to check you are training in the right zone.