Target Heart Rate Calculator

Five training zones based on the Karvonen formula. Knowing where to aim makes cardio actually work.

Your training zones

Maximum heart rate

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Why Karvonen + Tanaka

Two formulas, both better than the well-known "220 − age":

Tanaka (max HR) — 208 − 0.7 × age. From a 2001 meta-analysis. More accurate than "220 − age" especially for older adults.
Karvonen (zones) — uses your heart rate reserve (max − resting), not just max. Accounts for the fact that fit people have lower resting rates.

How to use the zones

Zone 2 is the "fat burning" zone — the most underrated. Long, slow distance work here builds aerobic base.
Zone 3–4 improves cardio fitness fastest, but is also the most demanding. Don't live here.
Zone 5 is short interval work — minutes, not hours.

A common split for endurance athletes: 80% of training in zones 1–2, 20% in zones 4–5, almost nothing in zone 3 ("the gray zone").