Heart Rate Zone Calculator

How to use

1. 1Pick a max HR formula: Tanaka (208 - 0.7 × age) for the modern default, Fox (220 - age) for the classic rule, or Custom to enter a measured max HR.
2. 2Enter your age in years, or for Custom enter your max HR in bpm. Optionally enter your resting HR (measured first thing in the morning).
3. 3Pick a zone method: Percentage of max HR (simple, no resting HR needed) or Karvonen (uses heart rate reserve, requires a resting HR).
4. 4Read your five training zones with bpm ranges, percent bands, and effort descriptions, then Copy summary to share or save the result.

About this tool

Heart Rate Zone Calculator turns your age (or a measured max HR) into the five standard training heart rate zones used for running, cycling, rowing, and other endurance training. Pick a max HR formula: Tanaka (208 - 0.7 x age), the peer-reviewed default that holds up better than 220 - age across a wide age range; Fox (220 - age), the classic rule of thumb most people still know; or Custom, where you enter a measured max HR from a lab test, a recent all-out effort, or a fitness watch. Pick a method: Percentage of max HR, where each zone is a fixed fraction of your max, or Karvonen, which uses heart rate reserve (HRR = max - resting) so zones adjust to your fitness. Lower resting HR shifts each Karvonen zone higher, which is why a well-trained athlete and a beginner of the same age get different prescriptions. The output is five zones with bpm ranges and percent bands: Zone 1 Recovery (50 to 60 percent, warm-up and easy days), Zone 2 Endurance (60 to 70 percent, the aerobic base for long runs and rides), Zone 3 Tempo (70 to 80 percent, steady state), Zone 4 Threshold (80 to 90 percent, lactate threshold work), and Zone 5 VO2 Max (90 to 100 percent, short hard intervals). Each zone shows the bpm range, the percent band, and a description so you know what the effort should feel like and what kind of training it supports. The summary panel shows your max HR, your resting HR, and your HR reserve at a glance, with a copy button for the full breakdown. Everything runs locally in your browser; your age, resting HR, and any measured numbers never leave your device. Useful for planning a polarized training week, sticking to Zone 2 for fat oxidation, finding the right pace for tempo intervals, or sanity-checking the zone numbers your fitness watch already shows. Personal max HR can vary by 10 to 20 bpm from any formula, so for the most accurate zones replace the calculated max with a measured value when you have one.

Free to use. Works in your browser. No signup, no login.