Half Marathon Pace Calculator — Min/km, Speed & Splits
Enter your half marathon finish time in hours, minutes and seconds to get your average pace per kilometre, pace per mile, speed in km/h and mph, and cumulative split times at every 5 km mark.
h
min
sec
= 4:59 per km
- 1
Total finish time
1 × 60 + 45 + 0 ÷ 60 = 105Convert hours, minutes and seconds to decimal minutes. - 2
Pace per km
105 ÷ 21.0975 = 4.98
How does this calculator work?
Pace (min/km) = finish time (min) ÷ 21.0975. Speed (km/h) = 60 ÷ pace. Multiply pace by 1.609344 for min/mile. A 1:45:00 finish gives a 4:58/km pace, 12.07 km/h, and 7:59/mi. Split times at each 5 km assume a perfectly even effort throughout the 21.0975 km race.
Formula
How this is calculated
A half marathon is the official World Athletics distance of 21.0975 km (13.1094 miles). This calculator divides your total finish time in minutes by 21.0975 to give your average pace in minutes per kilometre — the key figure for pacing training runs and race strategy.
The pace per mile multiplies the km pace by 1.609344, the exact kilometres-per-mile conversion. Speed in km/h is the inverse: 60 divided by the pace in min/km. Speed in mph then follows by dividing km/h by 1.609344.
The split-time bars show the cumulative elapsed time at 5 km, 10 km, 15 km, 20 km and the finish, assuming a perfectly even pace throughout. In practice most runners go through the first half slightly faster than the second — negative splits (faster second half) are associated with better race outcomes. These splits give an even-effort par to compare against a GPS watch. All calculations assume a certified flat course with no environmental adjustments.
Frequently asked questions
A half marathon is exactly 21.0975 km (13.1094 miles), defined by World Athletics. Some courses are very slightly longer to account for runner deviations, but the certified distance is always 21.0975 km.
Most beginners target 2:00–2:30 (a 5:41–7:06 min/km pace). Recreational runners often finish between 1:45 and 2:15. Elite runners finish under 1:00. Any finish is a great achievement — training consistency matters more than the initial time.
Multiply your min/km pace by 1.609344. For example, a 5:30/km pace equals 5.5 × 1.609 ≈ 8:51 per mile. This calculator shows the conversion automatically.
Also known as
TG we-Calculate Editorial Team. (2026). Half Marathon Pace Calculator — Min/km, Speed & Splits [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/half-marathon-pace-calculator
TG we-Calculate Editorial Team. "Half Marathon Pace Calculator — Min/km, Speed & Splits." TG we-Calculate. 2026. https://we-calculate.com/calculator/half-marathon-pace-calculator.
TG we-Calculate Editorial Team, "Half Marathon Pace Calculator — Min/km, Speed & Splits," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/half-marathon-pace-calculator
@misc{wecalculate_half_marathon_pace_calculator, title = {Half Marathon Pace Calculator — Min/km, Speed & Splits}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/half-marathon-pace-calculator}}, year = {2026}, note = {TG we-Calculate} }
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