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    Heat & Altitude Pace Adjustment

    Heat, humidity, and altitude all slow you down. Enter your ideal-conditions pace and the race environment to get a realistic adjusted pace and finish time.

    Conditions

    Your pace in cool, sea-level conditions is the baseline.

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    Last updated: June 2026Reviewed by: Bryan Collins, founder

    How this calculator works

    Above about 15°C, pace is slowed roughly 0.4% per degree Celsius, increased further in humid conditions. Above about 1000m, aerobic pace is slowed about 5-6% per additional 1000m of altitude. The two effects are combined and applied to your base pace.

    Assumptions

    • • Base pace reflects cool, sea-level conditions
    • • Representative heat and altitude slowdown coefficients

    Limitations

    • • Acclimatisation and individual tolerance vary widely
    • • A simplified model — not a substitute for race-day judgement

    Who this is for

    • • Runners and triathletes racing in heat or at altitude
    • • Athletes setting realistic goal paces for tough conditions

    Who this is not for

    • • Precise physiological prediction
    • • Athletes fully acclimatised to the conditions (impact is smaller)

    References

    Pace Adjustment Calculator FAQ

    Scientific References

    Ely MR, et al. Impact of weather on marathon-running performance. Med Sci Sports Exerc. 2007.

    Evidence on how ambient temperature affects endurance running pace