Train in the right zone
Five zones from your max heart rate — stop guessing your effort.
Results update as you type 🥑
What the zones mean
Heart-rate zones split effort into five bands of your maximum. Most training should sit in Zone 2 (easy/aerobic) to build an efficient engine without burning out.
Zones 1–2 build aerobic base and aid recovery. Zone 3 is the “grey zone” — useful but easy to overuse. Zones 4–5 build threshold and top-end speed and need real recovery.
We estimate max HR with the Tanaka formula, more accurate across ages than the old 220 − age. A lab or field test is more precise if you need it.
Common questions
Is 220 − age accurate?
It is a rough average with a wide error. Tanaka (208 − 0.7 × age) fits the population better, which is what we use.
What zone should I train in most?
For endurance, the majority of volume in Zone 2, with smaller doses of Zones 4–5. This “polarised” split works well.
Should I use heart rate or pace/power?
Heart rate is great for easy days; pace or power is more responsive for intervals. Many athletes use both.
Is my data stored?
No. Everything is calculated in your browser. Nothing is sent to a server or saved.
Sources & references
- Mifflin MD, St Jeor ST, et al. “A new predictive equation for resting energy expenditure in healthy individuals.” Am J Clin Nutr. 1990;51(2):241–247.
- Frankenfield D, Roth-Yousey L, Compher C. “Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults.” J Am Diet Assoc. 2005;105(5):775–789.
This calculator provides estimates for general educational use and is not medical advice. Consult a qualified professional before making significant dietary changes.