Running Performance Calculator
Enter your race result and its conditions (altitude, grade, heat, humidity, and wind) to find your true fitness equivalent at sea level in standard conditions.
Each factor is computed independently, then multiplied together to find the total condition penalty. Dividing your actual time by this multiplier gives your sea-level equivalent.
- Altitude: VO₂max declines roughly linearly with altitude; the tool applies a conservative ~3.2% performance penalty per 1,000m above 1,000m, from the reduced oxygen partial pressure of thinner air.1
- Course grade: the Minetti metabolic polynomial, C(i) = 155.4i⁵ − 30.4i⁴ − 43.3i³ + 46.3i² + 19.5i + 3.6 J/kg/m, normalised to the flat baseline of 3.6 J/kg/m. Net grade is used as a proxy for average gradient.2
- Heat & humidity: a penalty of roughly 0.3–0.45%/°C above 15°C that scales with race duration. Humidity is modelled as an increase in effective temperature, since it reduces evaporative cooling.3
- Wind: an aerodynamic drag model, ΔP = ½·C_d·A·ρ·Δv². Tailwind benefit is asymmetric and smaller than the equivalent headwind penalty.4
- Age: World Masters Athletics age-grading factors, linearly interpolated. They represent how much of peak physiological capacity remains at a given age, averaged across distance events.5
- 1Wehrlin JP, Hallén J. Linear decrease in VO₂max and performance with increasing altitude in endurance athletes. Eur J Appl Physiol. 2006;96(4):404–412.
- 2Minetti AE, Moia C, Roi GS, Susta D, Ferretti G. Energy cost of walking and running at extreme uphill and downhill slopes. J Appl Physiol. 2002;93(3):1039–1046.
- 3Ely MR, Cheuvront SN, Roberts WO, Montain SJ. Impact of weather on marathon-running performance. Med Sci Sports Exerc. 2007;39(3):487–493.
- 4Pugh LGCE. The influence of wind resistance in running and walking and the mechanical efficiency of work against horizontal or vertical forces. J Physiol. 1971;213(2):255–276.
- 5World Masters Athletics. Age-Grading Factors, revised 2023 (effective 1 January 2023).
Every coefficient here is a population average from a small study, and the factors are multiplied as if they were independent when they actually interact: heat compounds altitude, and wind’s cost depends on the air density that altitude changes. Net elevation also hides terrain, so a rolling course that nets to zero reads as flat.
Your real penalty also depends on things no slider can capture: heat acclimatization, sweat rate, body mass, haemoglobin mass, and days spent at altitude. Downhill isn’t free, and age-grading uses an average decline curve that well-trained masters runners routinely beat.
Vertical learns your personal response to heat, altitude, and terrain from your own GPS and heart-rate history instead of applying population averages, then folds those adjustments into each day’s target automatically. Your training reflects the conditions you actually run in, not the average runner’s.
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