What this result means
A half marathon is 21.0975 kilometres, or 13.109 miles. This calculator turns a target finish time into the average pace you must hold, plus speed and even splits. It does not predict a half from a shorter race.
Most road halves are certified at that distance. If your watch says 21.4 km, trust the course measurement for official time and this tool for target pace. For a marathon, open the marathon pace calculator. For equivalent times from a 10K, open the race time predictor.
A 1:45:00 half marathon requires about 4:59/km or 8:01/mile. Even splits put 10K near 49:50 and 10 miles near 1:20:10. A 1:30:00 half is about 4:16/km or 6:52/mile — a different goal, not a round-number cousin of 1:45.
A 2:00:00 half is about 5:41/km or 9:09/mile, close to a 4-hour marathon pace on paper and nothing like it in fueling or fatigue. Use this page for the half distance only.
Calculation method
Pace is finish time divided by 21.0975 km. Splits divide that time evenly. Displayed pace rounds to the nearest second. Speed is shown to one decimal place.
This is exact arithmetic, not an estimate of whether you can hold the pace. Riegel predictions and VDOT training bands live on other tools.
Even splits on a half often include a conservative first 3 km. Hills, heat, and a late drink-station walk are not in the table. The average is still the number the clock requires.
Frequently asked questions
What pace is a 1:45 half marathon?
About 4:59 per kilometre, or 8:01 per mile. That is an average. Even splits assume you hold it from the gun.
What pace is a 1:30 half marathon?
About 4:16 per kilometre, or 6:52 per mile. Enter 1:30:00 to see kilometre and mile checkpoints.
How long is a half marathon?
21.0975 kilometres (13.109 miles). This calculator uses that distance, not a round 21 km or 13 miles.
Can I predict my half from a 10K?
Not here. This tool converts a half-marathon target into pace. Equivalent race times use the race time predictor and Riegel’s formula.