Heart rate zone calculator

How to calculate your heart rate zones

1. Enter your age in years. Your max HR and 5 training zones appear instantly using the Tanaka formula.
2. Optionally enter your resting heart rate (measured first thing in the morning) to enable Karvonen personalised zones.
3. Review your 5 zones with bpm ranges and activity descriptions for each.
4. Use Zone 2 for base endurance training and Zone 4–5 for interval sessions.

Common uses

• Setting heart rate targets for a running, cycling, or rowing training programme alongside your calorie targets
• Implementing 80/20 training (80% in Zones 1 and 2, 20% in Zones 3 to 5) next to strength sessions planned from your estimated one rep max
• Calibrating a heart rate monitor or sports watch with personalised zones

Technical specification

• Algorithm or formula: Max HR via Tanaka et al. 2001 (208 − 0.7 × age). With resting HR, zones use the Karvonen reserve formula HR_zone = ((HRmax − HRrest) × intensity) + HRrest. Zone intensities span 50 to 100 percent in five bands.
• Browser API or library: Pure JavaScript arithmetic. No external library.
• Input limits: Age 1 to 120 years. Resting HR optional, accepted from 20 to 220 bpm and below your estimated max HR.
• Output: Maximum HR plus five zones with bpm ranges and activity descriptions (recovery, base endurance, aerobic, anaerobic threshold, max effort).
• Known limitations: All max-HR predictions carry roughly ±10 bpm individual variance. A graded exercise test gives a more accurate personal max HR.

Frequently asked questions

What are heart rate training zones?

Training zones are heart rate ranges tied to exercise intensity: Zone 1 is 50 to 60% of max HR (recovery), Zone 2 60 to 70% (base endurance), Zone 3 70 to 80% (aerobic and tempo), Zone 4 80 to 90% (threshold), and Zone 5 90 to 100% (maximum effort). Each zone produces different training adaptations. Results are estimates for informational purposes only.

Should I enter my resting heart rate?

Enter it if you know it. With a resting heart rate, the calculator switches to the Karvonen method and sets each zone on your heart rate reserve (max HR minus resting HR), which gives higher bpm values than the plain percentage-of-max table. Measure it in the morning before getting out of bed.

Do I need an account to use this calculator?

The calculator works without an account. Enter your age and your zones appear instantly. All calculations run in your browser. Our servers are not involved at any point.

What is the difference between the Tanaka and classic 220 minus age formula?

The Tanaka formula (208 − 0.7 × age) was validated in a meta-analysis of 351 studies involving 18,712 subjects (JACC 2001) and is more accurate than the classic 220 − age formula, particularly for adults over 40. Both are shown for comparison.