Free Training Tool
Get accurate training zones using the Karvonen (heart-rate-reserve) method. Max HR uses the research-backed Tanaka formula for men and Gulati for women — not the outdated 220 − age. Enter your resting HR for truly personalized zones.
Measure resting HR first thing in the morning before getting up. Typical range 50–70 bpm.
From a lab test or a maxed-out effort? Enter it to override the formula.
The old 220 − age rule was never derived from rigorous research and can be off by 10–20 bpm for many people. This tool uses Tanaka (208 − 0.7 × age) for men and Gulati (206 − 0.88 × age) for women — both validated against large datasets and far better predictors of actual maximum heart rate.
Rather than taking a flat percentage of max HR, Karvonen uses your heart-rate reserve (Max HR − Resting HR) and adds it back onto your resting rate: Target = Resting + Intensity × (Max − Resting). A fitter heart with a lower resting rate gets more individualized zones this way.
Zone 1–2 build your aerobic base and burn fat efficiently — most weekly volume should live here. Zone 3 is a productive aerobic grind. Zone 4 raises your lactate threshold. Zone 5 is short, maximal, anaerobic work. A polarized approach — lots of easy, some very hard — works well for most.
Formula estimates carry individual variance; a tested max HR is most accurate. Consult a physician before high-intensity training if you have cardiovascular risk factors. — Coach Scharnick, CSCS · B.S. Exercise Science