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Calculate race pace per mile or kilometer, finish time, and split times for any distance. Plan pacing for 5K, 10K, half marathon, and marathon.
Estimate VO2 max from race times, Cooper 12-minute test, or resting heart rate. Measure aerobic fitness for running and cycling training.
Calculate heart rate training zones from max HR, lactate threshold, or Karvonen formula. Set easy, tempo, threshold, and interval zones for running.
Divide total time equally by number of segments. Each mile or km checkpoint adds one unit of constant pace time.
Split N = Pace × N (cumulative time at segment N)Plan second half 1–3% faster than first half. Calculate first-half pace slightly slower than overall average, second-half pace slightly faster.
First half pace = Avg pace × 1.01; Second half = Avg pace × 0.99Start 2–5% slower than goal pace and finish at or below goal pace. Useful in crowded races or hot conditions where early restraint preserves late-race capacity.
Pace at mile N = Base pace − (Acceleration × N)Updated: July 2026
3:30 marathon = 8:01/mile. Mile splits: 8:01, 16:02, 24:03... Half at 1:45:00. Write splits on a wrist band for race day reference.
First half at 4:50/km (51:05), second half at 4:44/km (49:55). Total 1:40:00. Requires discipline to hold back in the first 5K.
Target 24:00 5K: km splits 5:05, 4:55, 4:50, 4:50, 4:20. Start conservative, build through middle km, all-out last kilometer.
Even pace on flat terrain differs from even effort on hills. Pre-plan adjusted splits using course elevation profile or run by perceived effort on climbs.
Negative splitting requires discipline to run slower than capability early. Practice in tempo runs and B races before attempting in a goal race.
Race splits break your target finish time into checkpoints at each mile or kilometer. Even splits hold constant pace throughout; negative splits run the second half faster; progressive splits start slow and accelerate. This calculator generates split tables for any distance and strategy.