Running Pace Calculator
Pace, finish time, splits and km↔mile pace conversion.
Overview
A running pace calculator converts between distance, time, and pace, and produces split tables for planning a race or training run. Given any two of the three core values, it computes the third — and then layers on useful extras like per-kilometre splits, halfway times, finish-time predictions, and a quick kilometre-to-mile pace conversion.
This is the single most-used calculator in distance running. Whether you are pacing a 10K negative split, planning a long run by feel, or trying to figure out what 7:45 per mile is in metric, the same arithmetic runs underneath every fitness watch, race chip, and coaching plan.
How it works
Pace is time / distance, expressed as minutes per kilometre or minutes per mile. Finish time is pace × distance. Speed is distance / time in km/h or mph. Conversions between pace and speed use the reciprocal: speed_kmh = 60 / pace_min_per_km. Mile-to-kilometre pace conversion uses the factor 1.609344, so a 6:00/mile pace is 6.0 / 1.609344 ≈ 3:44/km.
Splits are produced by stepping through each kilometre or mile mark and multiplying by pace, plus an optional positive or negative pacing bias for tactical splits. The tool keeps everything in seconds internally to avoid mm:ss rounding errors, then formats on output.
Examples
- Run 10 km in 50:00 → pace 5:00/km, 8:03/mile, average speed 12 km/h.
- Pace 4:30/km for 21.0975 km (half marathon) → finish time 1:34:57.
- Pace 8:00/mile for 26.2 mi → finish time 3:29:36; pace per km is 4:58.
- Even splits for a 25:00 5K → 5:00/km each, with a "negative split" preset shaving 5 s/km off the last 2 km.
FAQ
Is min/km or min/mile better?
Whichever the race course is marked in. Mismatching the two leads to subtle pacing mistakes over long distances.
How precise should splits be?
Most watches display to the second. In practice, even a well-paced runner varies by ±5–10 seconds per kilometre due to terrain and wind.
Can I plan walk-run intervals?
Yes — treat each segment with its own pace and sum the resulting times.
Why is my GPS distance slightly off?
GPS error accumulates around 1–2% on most watches, especially under tree cover or near buildings. Certified courses use measured wheels.