Why use Karvonen instead of % max HR?

Karvonen accounts for your resting HR. Two people with the same max HR can have very different fitness; the one with a lower resting HR has more "reserve" to use. % max HR ignores this and gives the same zones to everyone.

What if I take beta-blockers?

They suppress max HR by 20–40 bpm. None of these formulas work for you — train by RPE (rate of perceived exertion) instead, or get a sport-specific test from a clinic.

Heart Rate Zone Calculator

Your 5 training zones using the Karvonen formula — accounts for your resting heart rate, not just age.

Result

Estimated max heart rate

187 bpm

HR reserve (max − rest) = 122 bpm

Zone 1 — Recovery (50–60 %)Active recovery, warm-up126–138 bpm
Zone 2 — Endurance (60–70 %)Long easy runs, fat oxidation138–150 bpmHealthy
Zone 3 — Tempo (70–80 %)Aerobic threshold, "comfortably hard"150–163 bpm
Zone 4 — Threshold (80–90 %)Lactate threshold, race pace163–175 bpm
Zone 5 — VO2 max (90–100 %)Intervals, all-out efforts175–187 bpmBorderline

How to use this calculator

Get an accurate resting HR — first thing in the morning, before getting up, take a 60-second pulse.
Tanaka is more accurate than the classic 220 − age, especially over 40.
Zone 2 should feel easy enough to hold a conversation; if you can't, you're in zone 3.
Train mostly in zone 2 (80 %), sprinkle in zones 4–5 for intensity (20 %).

About this tool

Heart-rate-zone training matches your effort to a physiological purpose: zone 2 builds aerobic base, zone 4 raises your lactate threshold, zone 5 pushes VO2 max. The classic "220 minus age" formula ignores how individual resting heart rate varies — a fit 40-year-old with a resting HR of 50 has a much wider HR reserve than someone with a resting HR of 75. The Karvonen formula uses both numbers and gives more personalized zones. Most endurance athletes spend 80 % of training in zone 2 (where it feels too easy to be working) and only 20 % in zones 4–5.

Frequently asked

Your watch — actual measured max HR beats any formula. Formulas are starting points; if you have real data from an all-out 5K finish or hill repeats, use that as your max.