Heart rate zones calculator

Your five training zones - from max heart rate alone, or properly personalised with the Karvonen method if you know your resting HR.

Highest you've seen on a chest strap
Enables Karvonen zones - morning pulse before getting up

The five zones

  • Zone 1 - recovery. Genuinely easy. Warm-ups, cool-downs, the day after a race.
  • Zone 2 - endurance. Conversational. Where most of your weekly volume belongs - this is the engine-building zone.
  • Zone 3 - tempo. "Comfortably hard". Useful in doses; the classic trap is living here by accident.
  • Zone 4 - threshold. Around the effort you could race for an hour. Cruise intervals, tempo blocks.
  • Zone 5 - VO2max. 3-8 minute race effort and above. Short intervals, big recovery.

Max HR: formulas versus reality

This tool's age estimate uses Tanaka (208 − 0.7 × age), which beats the old 220 − age across most adults - but any formula carries ±10-15 bpm of individual error. If you own a chest strap, the highest reading from a hard race finish or hill-sprint session is a better max than any equation. Wrist optical sensors under-read at high intensity; trust straps for this.

Why resting HR makes zones better

Two runners with a max of 190 but resting rates of 40 and 70 are physiologically different people. The Karvonen method zones on your heart rate reserve (max − resting), so the fit runner's easy zone sits higher in raw bpm - which matches how it actually feels. If you gave a resting HR, the table above is Karvonen; if not, it's simple %max.

FAQs

My easy zone feels impossibly slow. Is it wrong?

Probably not - that reaction is nearly universal. If you've trained by feel for years, true zone 2 feels pedestrian for the first month. Hold the discipline; the aerobic gains follow.

Should I use HR zones for intervals?

Carefully - heart rate lags effort by a minute or more, so short reps finish before HR catches up. Use zones for steady running, and pace or effort for short intervals.

Do zones change as I get fitter?

Your resting HR drops and paces within zones get faster; max HR barely trains. Re-run the calculator when your resting HR shifts by more than a few bpm.