Cardio intensity calculator

Heart Rate Zones Calculator

Estimate five common training heart-rate zones from your age and resting pulse. Default max HR uses the Tanaka formula; intensity defaults to the Karvonen heart-rate reserve method.

How the formulas work

Estimated max heart rate (Tanaka, 2001): 208 − 0.7 × age. The classic Fox/Haskell estimate is 220 − age. Heart-rate reserve (Karvonen) is max HR − resting HR, and a target at a given intensity is resting HR + (intensity% × heart-rate reserve). The simpler alternative multiplies max HR by the same zone percentages.

Age-predicted max HR can be off by a wide margin for any one person. If you have a measured max from a supervised test, enter it as a custom value. These zones are general fitness planning estimates, not medical advice — stop if you feel dizzy, chest pain, or unusual shortness of breath, and talk with a clinician before intense training if you have cardiovascular risk factors.

Estimated max HR
187 bpm

Karvonen (heart-rate reserve). Heart-rate reserve: 127 bpm (max 187 − resting 60).

Training zones (Karvonen (heart-rate reserve))
ZoneIntensityHeart rateTypical use
Zone 1 — Very light50%60%124136 bpmWarm-up, recovery, easy movement
Zone 2 — Light / aerobic base60%70%136149 bpmSteady endurance and longer easy sessions
Zone 3 — Moderate70%80%149162 bpmTempo work; sustainable but noticeably harder
Zone 4 — Hard80%90%162174 bpmThreshold intervals; short hard efforts
Zone 5 — Near-max90%100%174187 bpmVery short max-effort intervals only

Pair zones with gym work

Use heart-rate zones for conditioning blocks, then keep strength work progressive with load and recovery tools below.