Target Heart Rate Calculator & Zones

This target heart rate calculator estimates your maximum heart rate and five training zones. Training by heart rate means working at the right intensity, not just 'hard'. This calculator estimates your maximum heart rate and turns it into five training zones, and — if you add a resting heart rate — computes Karvonen targets that account for your fitness.

Maximum heart rate

Tanaka:  maxHR = 208 − 0.7 × age
Classic: maxHR = 220 − age

Tanaka tracks measured values more closely across a wide age range, so it is the default here.

Zones and Karvonen

Zones are percentages of your maximum: zone 2 is 60–70%, zone 3 is 70–80% and so on. The Karvonen method instead uses heart-rate reserve — (max − resting) × intensity + resting — which raises the target for fitter people with a low resting rate. Measure your resting rate on waking for the best numbers.

Worked example

At age 40 the two formulas happen to agree exactly, which makes the arithmetic easy to follow: Tanaka gives 208 − 0.7 × 40 = 180, and the classic gives 220 − 40 = 180. With a resting heart rate of 60 the reserve is 120 beats:

Zone 2 (60–70% of max):  180 × 0.6 to 180 × 0.7  = 108 – 126 bpm
Karvonen zone 2:         120 × 0.6 + 60 = 132,  120 × 0.7 + 60 = 144
Zone 4 (80–90% of max):  144 – 162 bpm      Karvonen zone 4: 156 – 168 bpm

The Karvonen figures are consistently higher, and that gap is the whole point: a flat percentage of maximum ignores the fact that a fit person starts from a lower resting rate and therefore has more room to work in.

Why the two formulas diverge

They agree at exactly age 40 and disagree everywhere else. At 30, Tanaka gives 187 against the classic 190. At 60, Tanaka gives 166 against 160 — the classic formula now under-predicts. That direction matters, because an underestimated maximum produces zones that are too low, so an older adult following 220 − age trains below the intensity they are actually capable of.

Both remain population estimates with a standard error around 10 beats, meaning your true maximum could sit 20 beats either side of either figure. Athletes and anyone on rate-affecting medication — beta blockers most obviously — diverge further still. The only way to know your own number is a maximal field test or a lab measurement, and neither is worth pursuing unless you are training toward a specific competitive goal.

Getting a resting rate worth using

The Karvonen column is only as good as the resting heart rate you enter, and most people guess theirs too high. Measure it properly: on waking, before getting out of bed, before caffeine, and take the lowest of three consecutive mornings. A wearable that tracks overnight gives a reliable figure if you own one.

As for which zone to train in, most aerobic volume belongs in zones 2 and 3 (60–80%), which build endurance at a fatigue cost you can recover from daily. Zones 4 and 5 are for intervals and should be a minority of the week. The common error is spending every session in zone 3 — too hard to recover from and not hard enough to drive adaptation. BMR Calculator and TDEE Calculator cover the energy side of the same training plan, and Age Calculator is the quickest way to confirm the age you should be entering.

Private and precise

This calculator produces estimates from published formulas and is not medical advice. For anything about your health, talk to a doctor or a registered dietitian.