Running Pace Calculator

Your running pace (time per kilometer) is the basic number for managing training intensity and setting race goals. Enter any two of distance, time and pace and this tool calculates the third, along with projected times for common race distances (5K, 10K, half, full) and per-kilometer splits.

How to use this tool

Choose what to solve for, then fill in the other two values. For example, to find your pace after running 10 km in 55 minutes, select "Pace" and enter distance 10 and time 55 minutes. To work backwards from a goal, select "Pace" and enter your target race time and distance to see the per-km pace you need.

Reading the projections

Projected times assume you hold exactly the same pace to the finish. In real races pace drops as distance grows, so predictions from shorter races use conversion formulas such as Riegel's formula. Treat the values here as guides for setting training paces.

Tips

Pairing pace with heart-rate control keeps intensity consistent (Heart Rate Zone Calculator). Check calories burned with the Calories Burned Calculator and hydration with the Water Intake Calculator.

Choosing a race pace

Race pace should come from recent training and race results, not from the time you would like to run. A widely used shortcut estimates longer distances from a 5 km or 10 km result: doubling the distance typically multiplies the time by about 2.05–2.1. Someone running 10 km in 50 minutes is looking at roughly 1 hour 45 for a half marathon.

Even pacing and negative splits

The most efficient marathon strategy is generally even pacing, with a negative split (faster second half) close behind. Going out hard depletes glycogen early and buys a disproportionate slowdown later. Most recreational runners who fade badly did so because the first few kilometres were faster than the plan. Starting the opening 5 km some 5–10 seconds per kilometre slower than target pace is a sound habit.

Elevation and weather change everything

A pace built for a flat course does not survive different conditions. Each 1% of gradient costs several to a dozen seconds per kilometre uphill, and the descent rarely gives it all back. Temperature matters just as much: above about 20°C, every additional degree costs time, so summer racing requires a genuinely slower pace at the same effort. To manage effort by heart rate, see the heart rate zone calculator.