Target Heart Rate (Karvonen) Calculator
Find personalised training heart-rate zones with the Karvonen heart-rate-reserve method, which factors in your resting pulse.
How it works
HRmax = 220 − age · HR reserve = HRmax − resting HR · Target HR = reserve × intensity% + resting HR
The Karvonen method sets training zones from your heart-rate reserve — the gap between your maximum and resting pulse — rather than from max heart rate alone. Because it adds your resting rate back in, it personalises zones to your fitness: a well-trained heart with a low resting rate gets a different target than an untrained one of the same age. The 220 − age max is a rough population estimate, so if you know your true max from testing, use that for sharper zones.
Worked example
For a 30-year-old with a resting pulse of 60: HRmax = 190, reserve = 130. The lower bound at 50% is 130 × 0.50 + 60 = 125 bpm, and the upper at 85% is 130 × 0.85 + 60 = 170 bpm.
Sources: Karvonen method
Frequently asked questions
Why use heart-rate reserve instead of max heart rate?
Reserve-based zones account for your resting pulse, so they adapt to fitness level. A simple percentage of max heart rate ignores resting rate and can set zones too low for fit individuals.
How accurate is 220 minus age?
It is a population average with a spread of roughly ±10–12 bpm, so it suits general guidance. For precise zones, a lab or field max test beats the formula.
What zone should I train in?
Zone 2 (about 60–70% of reserve) builds aerobic base and can be sustained for long sessions, while zones 4–5 improve threshold and top-end fitness in short bursts. Most plans mix mostly easy work with some hard efforts.
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Educational estimate using standard formulas and population averages — not medical advice. Talk to a qualified clinician before making decisions about diet, training, or pregnancy.