How the Karvonen method works
Simple zone charts use a percentage of maximum heart rate. The Karvonen method is more individual because it accounts for your resting heart rate — two people the same age with resting rates of 50 and 75 get different zones. The calculator:
- Estimates max heart rate as 220 − age.
- Calculates heart rate reserve (HRR) = max HR − resting HR.
- Sets each zone as resting HR + (HRR × zone percentage): Zone 1 50–60%, Zone 2 60–70%, Zone 3 70–80%, Zone 4 80–90%, Zone 5 90–100%.
Worked example: Zone 2 for a 50-year-old
Age 50 with a resting heart rate of 60: estimated max is 170, so heart rate reserve is 110. Zone 2 is 60 + (110 × 0.60) to 60 + (110 × 0.70), or about 126–137 bpm.
Why Zone 2 gets so much attention
Zone 2 is steady, conversational-pace cardio — you can talk in full sentences but wouldn’t want to sing. Training here builds aerobic base and mitochondrial capacity with little recovery cost, which makes it a good fit alongside strength training. A common approach is several Zone 2 sessions a week plus a smaller amount of harder Zone 4–5 work.
Measure resting heart rate first thing in the morning, before getting up, on a few different days and use the average.
Frequently asked questions
What is my Zone 2 heart rate?
With the Karvonen method, Zone 2 is your resting heart rate plus 60–70% of your heart rate reserve (max HR minus resting HR). Enter your age and resting heart rate above to get your exact range.
How accurate is 220 minus age for max heart rate?
It is a population average with an error of roughly 10–12 bpm either way for individuals. Tanaka’s formula (208 − 0.7 × age) is a common alternative. A supervised exercise test gives the most accurate number.
Why does the Karvonen method use resting heart rate?
Including resting heart rate scales the zones to your current fitness. A fitter person with a lower resting rate gets zones that reflect their larger working range.
Do beta blockers affect heart rate zones?
Yes. Beta blockers and some other medications blunt heart rate, so formula-based zones may not apply. Use perceived effort and check with your doctor.