Pace & Split Calculator

Pace is simply time divided by distance, which makes it the single most useful number in distance running. A half marathon in 1:45:00 works out at 4:59 per kilometre, or 8:01 per mile. Knowing your pace lets you compare performances across different distances, plan workouts, and avoid the classic mistake of going out far too fast on race day.

The split table is where the maths earns its keep. If you run even splits, your time at each marker should climb by exactly one pace unit: 5K at 24:55, 10K at 49:50, 15K at 1:14:45, and so on. Almost nobody actually does this. Most runners start faster than their average and fade, which is why a positive split — a slower second half — is the norm and a negative split is a badge of honour. Running the first few kilometres a little slower than target pace costs a few seconds and often saves several minutes later.

Converting between kilometres and miles matters more than people expect, because races advertise in one unit and your watch may count in the other. One mile is 1.609 kilometres, so a 5:00 per kilometre pace is 8:03 per mile, not 8:00 flat. Over a marathon that difference of a few seconds per mile accumulates into a minute or two at the finish line.

A last note on the terrain. These are flat-ground numbers. Hills, heat, wind and altitude all slow you down, and the effect is far larger than most runners assume — a hot, humid day can add several minutes to a marathon. Use the number as a target for good conditions and adjust your expectations, rather than your effort, when the day is not ideal.

This calculator returns estimates for general information only. It is not medical advice, diagnosis or treatment, and it cannot replace an assessment by a qualified health professional. Individual results vary, and figures such as calorie needs, body-fat percentage and heart-rate zones are approximations based on population averages rather than measurements of you.