Training in the right heart-rate zone
Your heart rate is a real-time window into how hard your body is working. By training in specific heart-rate zones you can target different outcomes — building an aerobic base, burning fat, or improving speed — rather than exercising at one undifferentiated effort. This calculator personalises those zones using your resting heart rate, which makes them far more accurate than generic charts.
How to use the calculator
Enter your age and your resting heart rate (best measured first thing in the morning before getting out of bed). The calculator estimates your maximum heart rate and then gives you five target zones in beats per minute.
The Karvonen method
Rather than taking a flat percentage of your maximum, the Karvonen method works from your heart-rate reserve — the gap between your maximum and resting rates. The target for a given intensity is ((Max − Rest) × intensity%) + Rest, with maximum heart rate estimated as 220 − age. Because it factors in your resting rate, it adapts to your fitness level.
What the five zones do
Zone 1 (50–60%) is active recovery and warm-up. Zone 2 (60–70%) builds your aerobic base and burns fat at a conversational pace. Zone 3 (70–80%) develops aerobic endurance. Zone 4 (80–90%) sits at your lactate threshold — hard but sustainable. Zone 5 (90–100%) is all-out effort you can only hold for seconds. Most endurance training should sit in Zones 2 and 3, with short, occasional visits to the higher zones. This is a fitness guide, not medical advice — check with a doctor before starting intense exercise.