Heart Rate Zones Calculator
Training zones turn 'go for a run' into a dosage: Z1 recovery, Z2 aerobic base, Z3 tempo, Z4 threshold, Z5 VO2max - five bands with five different jobs. The catch is that every watch and wall chart computes them differently, and the two mainstream formulas disagree: % of max gives everyone the same bands, while the Karvonen method scales by heart rate reserve (max − resting) and hands trained hearts genuinely higher working zones for the same effort.
This calculator runs both, side by side with your resting heart rate factored in where it belongs, and keeps the honesty column open: 220 − age is a population average with over ±10 bpm of scatter on any individual. Your zones are remembered, shown in the tab title mid-workout, and shareable as a link that carries your settings.
How to use
- Enter your age and, if you know it, your resting heart rate.
- Pick Karvonen (reserve-based) or classic % of max.
- Train to the bands: most of your week belongs in Z2, and that's the one people skip.
Frequently asked questions
What are the 5 heart rate zones?
Z1 recovery (50-60%): warm-ups and flush-outs. Z2 aerobic base (60-70%): the conversational mileage that builds mitochondria - most of a training week lives here. Z3 tempo (70-80%): comfortably hard. Z4 threshold (80-90%): the effort you could hold for about an hour. Z5 VO2max (90-100%): intervals, minutes at a time.
Which formula is better, Karvonen or % of max?
Karvonen is physiologically fairer: it measures intensity relative to your usable range (reserve) rather than to a fixed max, so a fit athlete with a 45 bpm resting rate gets zones that reflect their engine. % of max wins only on convenience - no resting HR needed. Both inherit the 220 − age error.
How accurate is 220 minus age?
It is a 1971 population regression with no error bars on the wall chart: individual max HR at a given age scatters by more than ±10 bpm, and the formula drifts for older athletes. Tanaka's 208 − 0.7 × age fits modern data better. A field-tested max (hard finish to a race) beats any formula - use the formula until you have one.
Should I train by heart rate or pace?
Heart rate on hills, heat and tired days; pace on the flat and the track. HR drifts upward during long sessions (cardiac drift) and lags effort on intervals - so use zones to gate easy days and cap steady work, and use feel or pace for the sharp end. The best plan uses both loosely, not either rigidly.