Cardio
As of 2026-04-24
How Running Pace Calculator works
Methodology for the Running Pace Calculator: formulas, coefficients, data sources, assumptions, and known limitations.
Scope
Converts between time, distance, and pace; projects finish times across standard race distances.
Formula
pace = time / distance. finish_time = pace * distance.
Coefficients
| Parameter | Value | Note |
|---|---|---|
| 5K distance | 5.000 km | |
| 10K distance | 10.000 km | |
| Half marathon | 21.0975 km | |
| Marathon | 42.195 km |
Data sources
- World Athletics — Road Running Measurement procedures. — Federation rulebook for certified-course measurement and standard race distances.
- USA Track & Field — Course Certification Program. — U.S. governing body for road race course certification.
- Daniels JT. Daniels' Running Formula. 4th ed. Champaign, IL: Human Kinetics, 2021. — Source for the VDOT-based pace projection methodology used in projecting finish times across distances.
Assumptions
- Course is measured accurately; GPS watches typically over-report distance by 1–2%.
Approximation range
The arithmetic is exact. Residual error lives in distance measurement and GPS drift.
Limitations
- Ignores elevation, wind, and terrain.
Reproducibility
10 km in 50:00. Pace = 50/10 = 5:00/km. Half-marathon projection at same pace: 5:00 * 21.0975 = 1:45:29.
Change log
- 2026-04-24: methodology page first published.
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