Find your 5 personalised training zones for fat burn, aerobic fitness, threshold, and peak performance — using age or your measured max heart rate.
Training in the right heart rate zone is the difference between burning fat efficiently, building cardiovascular endurance, or pushing your anaerobic threshold. There are five universally recognised zones, each targeting a different physiological adaptation.
Zone 1 (very light, 50–60% max HR) is active recovery — great for warm-ups and rest days. Zone 2 (light, 60–70%) is the fat-burning and aerobic base zone, ideal for long steady sessions. Zone 3 (moderate, 70–80%) improves aerobic capacity and is the "comfortably hard" zone. Zone 4 (hard, 80–90%) is your lactate threshold zone — high intensity that improves speed and performance. Zone 5 (maximum, 90–100%) is all-out effort used in interval training.
The Karvonen method (Heart Rate Reserve) personalises zones using your resting heart rate, making it more accurate than a simple percentage of max. If your resting heart rate is high (detrained) or low (very fit), Karvonen adjusts your zones accordingly.
The most accurate method is a lab VO2 max test or a field test: after a thorough warm-up, run at maximum effort up a hill for 1–2 minutes, repeating 2–3 times. Your highest recorded heart rate is close to your max. The age formula (220 − age) is an estimate with ±10–12 bpm standard deviation.
Zone 2 (60–70% max HR) burns the highest proportion of calories from fat. However, higher-intensity zones burn more total calories per minute. For overall weight loss, a mix of Zone 2 steady-state and Zone 4 intervals is most effective.
The "80/20 rule" used by elite endurance athletes allocates roughly 80% of training volume in Zone 1–2 and 20% in Zone 3–5. Most recreational athletes train too much in Zone 3 and not enough in Zone 2 — the so-called "grey zone" that is hard enough to feel productive but not intense enough to drive performance gains.