Heart Rate Reserve Calculator
Calculate heart-rate reserve from maximum and resting heart rate, then create custom HRR-based target training ranges.
What heart-rate reserve means
Heart-rate reserve is the difference between maximum heart rate and resting heart rate. It represents the usable range between rest and maximal effort. Training zones based on reserve can be more personalized than zones based only on max heart rate.
Formula and custom target zones
The Cleveland Clinic heart-rate reserve guide explains the basic HRR calculation and its connection to the Karvonen method. This calculator lets you enter any intensity range, such as 60–75% HRR or 70–85% HRR.
How to use HRR in training
HRR is useful for endurance training because it accounts for your resting heart rate. If your resting heart rate drops with improved fitness, your calculated zones can shift even if your estimated maximum heart rate stays the same.
Limitations
Heart rate is affected by heat, dehydration, stress, caffeine, illness, sleep, and medications. Use it with perceived effort and sport-specific performance markers rather than treating it as perfect.
Frequently asked questions
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Max heart rate is the upper estimate or tested maximum. Heart-rate reserve subtracts resting heart rate, creating a personalized usable range.
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A tested max HR is better, but many people use estimates. If you do not know it, use the Karvonen calculator with age-based options.
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Different workouts target different intensity ranges. A custom field lets the same calculator handle easy aerobic work, tempo, threshold, and hard efforts.
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Yes. A lower resting heart rate changes HRR and therefore target zones.
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It can provide context, but it is not a complete fitness test. Combine it with performance, recovery, and training history.