Running Pace Calculator
What this pace projects to over a half and a full.
Reading your result
Fill in every field and the steps will be spelled out here.
How it is calculated
Distance projections run optimistic. Almost nobody holds 10km pace through a marathon; pace decays with distance and the decay itself grows. Real marathon times land slower than this arithmetic suggests, often by ten percent or more.
Pace and speed are the same number inverted. Six minutes per kilometre is ten kilometres an hour. Runners think in pace and treadmills display speed, so converting between them comes up constantly.
Working backwards from a target time is the more useful direction. A four-hour marathon is 5:41 per kilometre, and building sessions around that number is where a time goal actually starts.
Frequently asked questions
How far off are the projections?
Usually slower in reality — around 5% for a half stepping up from 10km, and 10% or more for a full. Higher training volume narrows the gap.
Can I enter speed instead?
Speed is shown alongside the result. For a treadmill session at 10km/h for 30 minutes, enter 5km and 30 minutes.
Why is pace written as minutes and seconds?
Time per kilometre is the most direct unit when running. Speed reads like a car dashboard and rarely gets used on the road.
Projections assume the pace holds for the full distance. Actual times vary with training, elevation, temperature and pacing strategy.