Heart Rate Zone Calculator – 5 Training Zones & Karvonen Formula

Heart rate zones are calculated using the Karvonen formula, which considers your maximum heart rate and resting heart rate. Max HR is estimated as 220 minus your age, then zones are determined as percentages of your heart rate reserve.

Resting heart rate (RHR) reflects cardiovascular fitness. A lower RHR generally indicates better fitness. For accurate zone calculations, measure RHR in the morning before getting out of bed, as it varies throughout the day.

Most training (60-70%) should be in Zone 2 (easy aerobic). Zone 3 (tempo) work comprises 10-20% of training. High-intensity zones (4-5) should be 5-10% of weekly volume to avoid overtraining.

Perceived exertion is useful for reference, but heart rate zones are more precise. However, if you can't use a monitor, the talk test can approximate zones: Zone 2 allows conversation, Zone 3 is difficult to talk, Zone 4+ is very hard to speak.

Chest strap monitors are typically 99% accurate. Wrist-based monitors vary in accuracy (85-95%) depending on fit and technology. For the most accurate zones, use a reliable heart rate monitor and get professionally fitted.

Zone 2: Can hold a conversation easily. Zone 3: Can speak in short sentences. Zone 4: Can only speak a few words. Zone 5: Cannot speak. This subjective measure correlates well with actual heart rate zones.