How it works
This calculator uses the Karvonen method, also called the heart-rate reserve method. It accounts for your resting heart rate, so it is more personalized than the simple "220 minus age" rule alone.
The formula for each zone is:
Zone BPM = ((220 − age − RHR) × intensity%) + RHR
Where RHR is your resting heart rate. The result is a set of five training zones:
- Zone 1 (50–60%): Recovery and warm-up. Easy conversation pace.
- Zone 2 (60–70%): Aerobic base. The classic "easy" zone for building endurance.
- Zone 3 (70–80%): Tempo. Moderately hard; sentences become shorter.
- Zone 4 (80–90%): Threshold. Hard effort, sustainable for minutes.
- Zone 5 (90–100%): VO₂ max / sprint. Very hard, short intervals.
Limitations
The "220 minus age" max-heart-rate estimate has a standard deviation of about 10–12 bpm, meaning it can be off significantly for any one person. A lab test or field test gives a more accurate maximum. Medications such as beta blockers can also suppress heart rate, making zones based on formulas unreliable.