Aerobic-Anaerobic Threshold Calculator

About this calculator

Aerobic and anaerobic thresholds mark two key transition points in exercise intensity: the aerobic threshold is roughly where the body shifts from relying mostly on fat as fuel to a meaningful contribution from carbohydrate, while the anaerobic threshold (close to what's often called lactate threshold) is the intensity above which lactate starts accumulating in the blood faster than it can be cleared. Without lab testing (like a lactate or gas-exchange test), these thresholds are commonly estimated from age-predicted maximum heart rate and resting heart rate, applying typical percentage bands — aerobic threshold around 70-80% of heart-rate reserve, anaerobic threshold higher again.

Coaches and endurance athletes use these estimated thresholds to define training zones for base-building runs and rides (below aerobic threshold), tempo or threshold work (between the two), and high-intensity intervals (above anaerobic threshold), without needing access to a physiology lab. It's a practical, low-cost substitute for direct lactate or VO2 testing, understood to be an estimate rather than a precise physiological measurement.

This calculator takes your age and resting heart rate and returns estimated aerobic and anaerobic threshold heart rates to guide your training zones.