Aerobic vs Anaerobic Threshold Calculator

About this calculator

VT1, the aerobic or first ventilatory threshold, marks the pace you can hold while still talking comfortably, where fat oxidation still dominates energy production. VT2, the anaerobic or lactate threshold, marks the point where lactate starts accumulating in the blood faster than the body can clear it. Without lab testing, both are commonly estimated as percentages of maximum heart rate.

Endurance coaches use these two thresholds to define training zones: everything below VT1 is easy base training, the zone between VT1 and VT2 is tempo or threshold work, and anything above VT2 is anaerobic/VO2max territory. Knowing where your own thresholds sit matters directly for marathon and half-marathon pacing and for structuring a training block correctly.

This calculator takes your maximum and resting heart rate and returns your estimated VT1 and VT2 heart rates, plus the training zone that sits between them.