Heart Rate Zone Calculator
Your training zones based on age and resting heart rate.
Z1 Recovery
Karvonen: 125–138 bpm · %MHR: 95–114 bpm
Z2 Aerobic base
Karvonen: 138–151 bpm · %MHR: 114–133 bpm
Z3 Tempo
Karvonen: 151–164 bpm · %MHR: 133–152 bpm
Z4 Threshold
Karvonen: 164–177 bpm · %MHR: 152–171 bpm
Z5 VO2 max
Karvonen: 177–190 bpm · %MHR: 171–190 bpm
About
Cardio is more effective when you target specific heart-rate zones. This calculator uses the Karvonen formula (heart-rate reserve) for personalized zones based on your age and resting heart rate, plus shows the simpler max-HR percent zones for comparison.
How to use
- Enter your age and resting heart rate (measure first thing in the morning).
- See your max HR estimate and your 5 training zones (Karvonen and %MHR).
FAQ
What's wrong with the 220 - age formula?+
It's a rough average and is off by 10 to 20 bpm for many people. Karvonen accounts for individual fitness via resting HR, which is a better proxy.
What's zone 2 used for?+
Zone 2 (60 to 70% of HRR) is the aerobic base zone. Long, low-intensity efforts here build mitochondrial density, fat oxidation, and capillary density. The bulk of endurance training should happen here.