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.

How do I find my resting heart rate accurately?

Take your pulse for 60 seconds first thing in the morning, before getting out of bed, on three consecutive days and average them. Most fitness trackers also report a daily resting HR overnight, which is typically within 1–2 bpm of the manual measurement.

Are there different zone systems?

Yes — common ones are 5-zone Karvonen (used here), Joe Friel's 7-zone power/HR system, and Maffetone's 180-minus-age aerobic ceiling. They mostly agree on the boundary between conversational (zone 2) and threshold (zone 4) training.

Heart Rate Zone Calculator — embedded

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

65 bpm144 bpm187 bpm

Marker at zone-2 mid (144 bpm) — most endurance training should sit here.

Resting HR (input)

65 bpm

Max HR (estimated)

Tanaka 208 − 0.7×age

187 bpm

HR reserve (HRR)

used by Karvonen formula

122 bpm

Source: Karvonen et al., Ann Med Exp Biol Fenn 1957; Tanaka et al., J Am Coll Cardiol 2001

Not medical advice — Formulas are population estimates; actual max HR can vary ±10–15 bpm. If on beta-blockers or with cardiac history, train by RPE and consult a sports physician.

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.

How it works — the formula

Tanaka max HR  = 208 − 0.7 × age
Karvonen target = ((maxHR − restingHR) × intensity%) + restingHR

The Tanaka 2001 meta-analysis of 351 studies found 208 − 0.7·age fits actual measured maxima better than the older 220 − age, especially over age 40. The Karvonen 1957 method uses heart-rate reserve (max minus resting) to scale intensity, so two athletes with the same max HR but different fitness train at appropriately different absolute heart rates.

Sources: Tanaka H, Monahan KD, Seals DR — Age-predicted maximal heart rate revisited (J Am Coll Cardiol 37(1) 2001) · Karvonen MJ, Kentala E, Mustala O — The effects of training on heart rate (Ann Med Exp Biol Fenn 35(3) 1957) · ACSM Guidelines for Exercise Testing and Prescription, 11th ed.

Worked examples

Example 1

40-year-old, average resting HR

Inputs:: age = 40, resting HR = 65
Output:: Max HR ≈ 180 bpm; zone 2 (60–70% reserve) ≈ 134–146 bpm

Example 2

Highly fit cyclist with low resting HR

Inputs:: age = 35, resting HR = 45
Output:: Max HR ≈ 184 bpm; zone 4 (80–90%) ≈ 156–170 bpm

Example 3

Older recreational runner

Inputs:: age = 60, resting HR = 70
Output:: Max HR ≈ 166 bpm; zone 2 ≈ 128–138 bpm

Limitations

Population formulas have a standard deviation of ±10–15 bpm versus measured maximum heart rate.
Beta-blockers, calcium-channel blockers, and other cardiac medications invalidate these zones — use rate of perceived exertion or talk to a sports physician.
Heat, dehydration, illness, and altitude all temporarily shift heart-rate response by 5–15 bpm.
Karvonen requires an accurate resting heart rate — measure it before any caffeine and after waking.

Heart-rate zones are training guides, not medical thresholds. This calculator does not provide medical advice — anyone with cardiovascular disease, arrhythmia, or who is on heart medication should consult a cardiologist before structured HR-zone training.

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.