Target Heart Rate Calculator (Karvonen Formula)
Find your target heart rate zones from your age and resting heart rate
Enter your age and resting heart rate, and this calculator uses the Karvonen formula to work out your maximum heart rate and heart rate reserve (HRR), then maps out target heart rate ranges for every intensity level, from an easy warm-up all the way to the anaerobic threshold. It's built for anyone who wants to dial in the right intensity for cardio or fat-loss training. Everything is calculated right in your browser, so nothing you enter is ever sent to a server.
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How to use
- Enter your age in years.
- Enter your resting heart rate in bpm (best measured first thing in the morning, before you get out of bed).
- Your maximum heart rate and heart rate reserve (HRR) are calculated automatically.
- Review the four target heart rate zones, from active recovery up to high-intensity anaerobic work.
FAQ
- How does the Karvonen formula actually work?
- It subtracts your resting heart rate from your maximum heart rate (HRmax = 220 − age) to get your heart rate reserve (HRR), multiplies that by the intensity percentage you're targeting, and adds your resting heart rate back in.
- How is this different from a plain age-based estimate?
- The Karvonen formula factors in your resting heart rate, which reflects your cardiovascular fitness. That gives you target zones tuned to your actual conditioning instead of a one-size-fits-all number.
- Which zone is best for burning fat?
- The 60–70% intensity range is generally considered the fat-burning aerobic zone, where your body relies most efficiently on fat for fuel.