Karvonen Heart Rate Zones Calculator

Target HR = ((max HR − resting HR) × intensity) + resting HR. The HRR (heart rate reserve) method.

Result

Loading calculator…

—

How to use this calculator

Measure true resting HR (lying in bed before getting up).
Estimate or test max HR.
Read the zone you want to train in.
Heart rate strap > optical for accuracy.

About this calculator

The Karvonen formula uses heart rate reserve (HRR = max HR − resting HR) instead of just max HR. This better accounts for fitness level — a fitter person with lower resting HR gets larger HRR and slightly different zones than the simple %-of-max method. A 40-year-old with rest 60 and max 185: HRR = 125. Z2 (aerobic base) is then 60% × 125 + 60 = 135 bpm to 70% × 125 + 60 = 147 bpm. Lower than the naive 60-70% of max (111-130).

Frequently asked

Why Karvonen vs. % of max?+

% of max under-counts effort at low intensities — a dead-still resting "0% effort" still has a HR. Karvonen anchors to your reserve, which is more honest.

How do I find true resting HR?+

Lie in bed motionless for 5 min before getting up. Use a chest strap or pulse-check at the wrist. Optical watches at rest read ±5 bpm.

Are 5 zones standard?+

Yes for most coaches. Some elite programs use 7 zones (Coggan/Friel). The 5-zone model is universal for general fitness.

What if I don't know my max HR?+

Use max-hr-by-age. The Tanaka formula (208 − 0.7 × age) is more accurate than the old 220 − age, especially over 40.

Does Karvonen apply to cycling and running equally?+

Yes — heart rate reflects systemic effort regardless of mode. Cycling HR tends to read 5-10 bpm lower than running at same effort due to muscle pump differences.