Find your optimal exercise heart rate zones using the Karvonen formula. Enter your age and resting heart rate to get personalized target zones for every workout intensity.
Enter your age — The calculator uses the Haskell-Fox formula (220 - age) to estimate your maximum heart rate.
Enter your resting heart rate — Measure your pulse first thing in the morning for the most accurate reading. The calculator uses the Karvonen formula to compute personalized zones based on Heart Rate Reserve.
View your zones — Five zones are displayed with exact bpm ranges and descriptions for each intensity level: from warm-up (Zone 1) to maximum effort (Zone 5).
The tool uses the Karvonen formula: Target HR = ((Max HR − Resting HR) × %Intensity) + Resting HR. First, max HR is estimated as 220 − age. Then heart rate reserve (HRR) is calculated as max HR minus resting HR. Each zone's range is then computed as a percentage of HRR, added to your resting HR. This method gives more accurate, personalized zones than using percentage of max HR alone.
Max HR is commonly estimated as 220 minus your age (Haskell-Fox formula). For a 30-year-old, that gives 190 bpm. This is an average estimate — your true maximum can vary by ±10 bpm.
Zone 2 (60-70% of heart rate reserve) is often called the "fat-burning zone" because the body relies primarily on fat oxidation at this intensity. For sustained fat loss, most trainers recommend a mix: long Zone 2 sessions for volume and shorter Zone 3-4 intervals for metabolic boost.
Measure your pulse first thing in the morning before getting out of bed. Count beats for 60 seconds, or for 30 seconds and multiply by two. Take the average over 3-5 mornings for the most accurate reading. Most adults fall between 60-80 bpm.
Zone 5 (90-100% of max HR) should only be sustained for short bursts — typically 10-30 seconds during HIIT. Prolonged time in Zone 5 significantly increases injury risk. Best reserved for experienced athletes.
The Karvonen formula calculates heart rate zones using Heart Rate Reserve (max HR minus resting HR). By including your resting HR, it gives more personalized and accurate zones than using percentage of max HR alone. A fitter person with a lower resting HR gets higher, more accurate target numbers.
Zone 2 for base endurance (aim for 80% of weekly volume), Zone 3-4 for tempo and threshold work, Zone 5 for HIIT intervals. Always warm up 10-15 minutes in Zone 1-2 before intense intervals to prevent injury.