Karvonen Heart Rate Calculator
Dial in your training zones using the Karvonen method, which factors in your resting heart rate for a target range that's actually tailored to you.
The Karvonen method uses your heart-rate reserve — the gap between your max and resting rates — so it personalizes zones better than a flat percentage of max. A lower resting heart rate (a sign of fitness) shifts every zone. Measure your resting rate first thing in the morning for the truest number.
How it works
The Karvonen formula is straightforward: target heart rate equals your heart-rate reserve (max minus resting) times the intensity you want, added back to your resting rate. In symbols, THR = ((max − rest) × intensity%) + rest.
Your max heart rate can come from the classic 220 − age estimate, or you can type in a number from a lab test or a hard max-effort session if you've got one. Resting heart rate is best measured first thing in the morning before you get up.
Because it starts from your resting rate, this method gives fitter people (who tend to have lower resting rates) different, more personalized zones than a plain percentage of max would. Set an intensity and you'll get a single target plus a full five-zone breakdown.
Frequently asked questions
Why is Karvonen better than just a percentage of max?
Because it accounts for your resting heart rate. Two people with the same max but different fitness levels get different targets, which better reflects the actual strain each is under at a given effort.
How accurate is 220 − age?
It's a rough population average and can be off by 10–20 beats for any individual. If you've ever seen your true max in a hard effort, enter that instead for a more honest result.
What intensity should I train at?
It depends on the goal. Easy aerobic base work sits around 60–70%, tempo around 70–80%, and threshold or interval work climbs above 80%. Most training plans mix zones rather than living in one.