What does this tool do?
Heart Rate Zones calculates your five training heart-rate zones from your age and resting heart rate. Runners, cyclists, and anyone tracking their fitness can see which pulse range they are working in, expressed in bpm. The calculation runs entirely in your browser.
How to use it
- Enter your values into the fields.
- The result is calculated instantly.
- Read or copy the result.
Five zones and the Karvonen method
The tool shows five zones based on percentages of your maximum heart rate: Warm Up (50–60%), Fat Burn (60–70%), Cardio (70–80%), Anaerobic (80–90%), and Max Effort (90–100%). Max heart rate is derived from the 220 − age formula when you leave it as '0=auto', or you can enter a value from a lab test manually. With the Karvonen method box ticked, the calculation also factors in your resting heart rate (heart-rate reserve), giving more personal, accurate ranges.
Guide your training
In the lower zones (Warm Up, Fat Burn) you do long, easy endurance work; the Cardio zone builds aerobic capacity, while Anaerobic and Max Effort are for short, intense intervals. Enter your age, resting heart rate, and an optional max value to set your zones, then use a heart-rate watch or chest strap to stay within these bpm ranges during a session for the training effect you want.
Frequently asked questions
What does the Karvonen method change?
Karvonen calculates zones from your heart-rate reserve (maximum minus resting) rather than maximum heart rate alone. This produces more personalized and usually higher lower bounds, especially for people with a low resting pulse.
Why can I enter the max heart rate manually?
220 − age is only an estimate. If you know your true maximum from an effort test, entering it (overriding auto) gives far more accurate zones.
Are the calculated values medical advice?
No. They are estimated ranges to help plan training. If you have a health condition or are just starting out, consult a physician.
Is Heart Rate Zones free?
Yes. Heart Rate Zones and all 300+ tools on MagmaNex are completely free with no signup or account required.
Is my data safe?
Yes. Everything runs locally in your browser. The data you enter is never sent to a server, stored, or shared.
Does it work on mobile?
Yes. Heart Rate Zones works on phones, tablets and desktops — no app download needed.
🔒 Privacy: everything runs in your browser, your data is never sent to a server.