PaceCalc is a calculator, not a coach. It applies stated formulas to the numbers you enter and shows the result. Nothing here is training advice, medical guidance, or a promise about what your body can do.

What the numbers are — and aren’t

• Arithmetic is exact; predictions are estimates. A 10K in 50:00 is exactly 5:00/km and 12 km/h — that’s conversion math. A Riegel marathon prediction is a statistical estimate with a stated window — it knows nothing about your mileage, health, course or weather, and it will be wrong for some runners.
• Training zones are heuristics. The percentage bands come from common coaching conventions applied to a formula-derived anchor — not from a lab test of your thresholds. Individual physiology varies by more than the bands’ width.
• Fitness claims are population-level. Benchmarks like “a good pace” describe distributions, not judgments about you. Age, health history and circumstances move individual cases well off any table.

Training decisions worth more than a calculator

Before starting, intensifying or changing an exercise program — especially with any health condition, injury history, or after a long layoff — talk to a physician. For structured training, a qualified running coach who sees your actual running is worth more than any formula, ours included.

Liability

The site is provided “as is” without warranties of any kind. We work to keep the math correct and the explanations honest — if you find an error, tell us and it gets fixed first. PaceCalc may earn revenue from advertising shown on the site; ads never influence the numbers or the content.