Altitude Pace Adjustment Calculator

About this calculator

Air at altitude has lower barometric pressure, which reduces the partial pressure of oxygen available to your lungs and blood, cutting into the oxygen delivery that fuels aerobic running — the higher you go, the smaller each breath's oxygen payload becomes. The effect is roughly negligible below about 1,500 m, then grows steeper with elevation, while partial acclimatisation over days to weeks lets the body compensate somewhat through increased red blood cell production and breathing efficiency.

Runners racing or training at elevation — from mountain trail races to simply visiting a higher-altitude city — use altitude pace adjustment to avoid starting a race at sea-level effort and blowing up, translating a goal pace into a realistic altitude-adjusted pace and finish time instead. Coaches also use it to set fair expectations for athletes traveling from sea level to compete at venues like Mexico City or Colorado mountain races.

This calculator takes your target pace, the elevation you'll be running at, and your acclimatisation level, and estimates how much slower your pace and finish time will be due to the reduced effective oxygen availability.