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Heart rate zone calculator

Turn your age, resting heart rate or measured max into five training zones and their purpose.

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Heart rate zone calculator
Paste your age and resting heart rate — one person per line — and this tool works out the boundaries of your training zones and what each one is for: recovery, endurance, tempo, threshold or maximum effort. It's built for runners, cyclists and anyone following a heart-rate-based training plan who wants zones matched to their own numbers instead of a generic chart, and it handles a whole team or training group just as easily as a single line.
Choose the zone method: percentage of max heart rate is the simplest, while the Karvonen method factors in your resting heart rate for a heart rate reserve that adapts better to fitter athletes. If you don't have a measured maximum, pick the Tanaka or Fox formula to estimate it from age; if you do — from a max-effort test or a recent race — turn on "Use a measured maximum heart rate" and add it as a third value on the line. You can also choose 3, 5 or 7 zones, switch the display between beats per minute and percentages, and pick text, table or CSV output — the table adds a recommended session duration for each zone.
The tool accepts Windows and Unix line endings interchangeably, validates that resting heart rate is always lower than the maximum, and reports a clear error with the line number if an entry doesn't parse. Very large batches are capped at a sane output size so the page never freezes trying to render more than a browser tab should hold.
Everything runs locally in your browser — nothing you type is uploaded anywhere. Copy the result, download it as a .txt file, or send the output straight back into the input to try another method or zone count on the same numbers.
FAQ
What's the difference between the two zone methods?
Percentage of max heart rate takes a simple fraction of your maximum. The Karvonen method adds your resting heart rate into the calculation (as heart rate reserve), which usually gives more personalized zones, especially for very fit or very unfit people.
Should I use an estimated or a measured maximum heart rate?
A measured maximum from a supervised max-effort test or a hard race is more accurate than any formula. If you only have your age, the Tanaka and Fox formulas give a reasonable estimate, but they can be off by 10–20 bpm for some people.
How many zones should I choose?
Five zones is the most common model and matches most training plans. Three zones is simpler for casual training; seven gives finer control if you follow a more structured, polarized program.
Are these zones exact enough to replace advice from a coach or doctor?
No. They're a general guide based on widely used formulas, not a medical or physiological assessment. Talk to a doctor before starting a new training program, especially with any heart condition.
Is my data uploaded anywhere?
No. Every calculation runs entirely in your browser — the ages and heart rates you enter never leave your device.