How to use it
- Enter your age in years.
- Enter your resting heart rate (bpm).
- Click Calculate to see your Zone 2 and Zone 3 ranges.
- Use the numbers to set your workout targets.
The Heart Rate Zone Calculator uses the Karvonen method to turn your age and resting heart rate into exact training zones. First it estimates your maximum heart rate (220 − age), then subtracts your resting rate to get the reserve. Multiplying the reserve by the 60‑70 % and 70‑80 % intensity ranges gives you Zone 2 and Zone 3 lower and upper limits. Zone 2 is the sweet spot for building aerobic base, while Zone 3 improves cardiovascular capacity. The results appear as four numbers: the lower and upper beats‑per‑minute for each zone. Use the lower bound to start a session and the upper bound to know when you’re pushing too hard. Keeping your effort inside these bands maximizes fitness gains and minimizes over‑training risk. You can re‑run the calculator whenever your fitness improves to adjust the zones.
Pro tips
- Round the results to the nearest whole beat; heart‑rate monitors work in whole numbers.
- Enter your resting heart rate taken first thing in the morning for accuracy.
- If you train with a chest strap, set your target HR between the lower and upper values, not at the midpoint.
- Double‑check that you entered age in years, not months, to avoid inflated zones.
Real-life examples
- A beginner runner wants to know the exact HR range for easy long runs.
- A cyclist plans interval sessions and needs Zone 3 boundaries to gauge effort.
- A personal trainer creates customized cardio plans for clients of different ages.
Case study
Maria, 38, thought she was training too hard. Using the calculator she discovered her Zone 2 was 118‑138 bpm, not the 150 bpm she was using. After adjusting her runs to stay within the proper range, her weekly mileage increased by 20 % without fatigue, and her 5K time dropped 2 minutes.