Target Heart Rate Zones Calculator
Find your 5 training zones based on age, with optional Karvonen calculation.
Enter your age. Optionally add your resting heart rate for more accurate zones via the Karvonen formula.
How max heart rate is estimated
The simplest formula is 220 minus your age. So a 40-year-old has an estimated max heart rate of 180 bpm. This is an estimate that can be off by 10-20 bpm in either direction for individuals. For an accurate max, athletes use lab-based VO2 max testing or a supervised stress test.
The five training zones
- Zone 1 (50-60% of max): very light. Recovery and warm-up. Conversation easy.
- Zone 2 (60-70%): light. Builds aerobic base. Can hold a conversation. The "fat-burning zone."
- Zone 3 (70-80%): moderate. Aerobic conditioning. Talking gets harder.
- Zone 4 (80-90%): hard. Lactate threshold work. Short sentences only.
- Zone 5 (90-100%): max effort. Intervals only, can hold for seconds to a few minutes.
Karvonen formula (more accurate if you know resting HR)
The Karvonen method uses heart rate reserve (max minus resting) to set zones. This accounts for individual fitness level. If you provide your resting heart rate, this calculator uses Karvonen automatically. To measure resting HR, take your pulse for a full minute first thing in the morning before getting out of bed.
What zones to train in
Most endurance training research suggests an 80/20 split: 80 percent of weekly volume in zones 1-2 (easy), 20 percent in zones 4-5 (hard). Zone 3 is often called the "junk miles" zone because it is too hard for easy days and too easy for hard days. This applies to runners, cyclists, and swimmers; weightlifters and HIIT athletes follow different patterns.
Informational only. This calculator is not medical advice and does not diagnose, treat, or prevent any condition. Always consult a qualified healthcare provider for medical decisions.