Zone 2 Heart Rate Calculator

What is Zone 2 training?

Zone 2 is a low-to-moderate intensity effort at which the body primarily burns fat for fuel and builds aerobic base capacity. It corresponds to a comfortable, conversational pace — you can speak in full sentences but feel a slight increase in breathing effort.

Zone 2 training improves mitochondrial density, fat oxidation efficiency, and cardiac output. It is the foundation of most endurance training programmes and is increasingly recognised for metabolic health benefits beyond sport, including insulin sensitivity improvements and cardiovascular risk reduction.

Calculation methods

Percentage of max HR (simplest): Zone 2 = 60–70% of estimated maximum heart rate. Max HR is estimated with the Tanaka formula (208 − 0.7 × age), which outperforms the older 220 − age formula across a wide age range.

Karvonen heart rate reserve: Zone 2 = 60–70% × (maxHR − restingHR) + restingHR. By anchoring the calculation to resting heart rate, this method produces a personalised range that accounts for individual fitness level — a fitter person with a lower resting HR will get a different Zone 2 range than a sedentary person of the same age.

Maffetone 180-formula: Zone 2 ceiling = 180 − age. This method was developed for aerobic base building and gives a conservative upper limit. It does not require a resting heart rate measurement.

Training in Zone 2

Zone 2 sessions are typically 45–90 minutes at a steady, aerobic effort. Common activities include cycling, running, rowing, and brisk walking. A simple field test: you should be able to hold a conversation without gasping.

Heart rate monitors can drift during exercise due to sweat and movement artefact. Chest strap monitors generally provide more accurate real-time data than optical wrist-based monitors, especially during lower-intensity steady-state efforts.