Tool 07 — Training
Heart Rate Zone Calculator
Find your five training zones from your age. Add your resting heart rate for personalized Karvonen zones — no email wall, no account.
Your Stats
Measure first thing in the morning, before getting up.
The Basics
What Are Heart Rate Zones?
Heart rate zones divide your effort range — from easy recovery to all-out sprint — into five bands based on percentages of your maximum heart rate. Each zone trains a different energy system, so knowing your zones turns "go for a run" into a precise training stimulus.
Zone 2 Base
The engine room. Zone 2 improves mitochondrial density, fat oxidation, and cardiovascular efficiency — the adaptations that support everything else.
Threshold
Zone 4 work raises the pace you can sustain before lactate accumulates — the single biggest predictor of endurance performance.
VO₂ Max
Short Zone 5 intervals push your maximal oxygen uptake — a top marker of both performance and long-term health.
Why Max HR Formulas Are Estimates
No equation knows your genetics. Real max heart rate varies by roughly ±10–12 bpm from any age-based prediction, which is why zones are given as ranges, not single numbers. Medications (especially beta-blockers), caffeine, heat, altitude, sleep, and fatigue all shift your heart rate on any given day.
Use the "talk test" as your reality check: if you're supposedly in Zone 2 but can't hold a conversation, the number matters less than the effort. Adjust the zone bounds to match how the pace actually feels.
Questions
Heart Rate Zone FAQ
How do you calculate maximum heart rate?
The traditional formula is 220 minus your age. The more accurate Tanaka formula is 208 − (0.7 × age), based on a meta-analysis of over 18,000 subjects. For a 32-year-old, Tanaka estimates 208 − 22.4 ≈ 186 bpm. Individual max HR can vary by ±10–12 bpm from either estimate.
What is Zone 2 cardio and why does everyone talk about it?
Zone 2 is 60–70% of your max heart rate — a pace where you can still speak in full sentences. It builds your aerobic base: more mitochondria, better fat oxidation, and improved cardiovascular efficiency. Most elite endurance athletes spend around 80% of their training volume here because it drives adaptation with very little recovery cost.
What is the Karvonen method?
The Karvonen (heart rate reserve) method personalizes zones using your resting heart rate: Target HR = resting HR + intensity% × (max HR − resting HR). Because fitter people have lower resting heart rates, Karvonen zones automatically shift as your fitness changes, making them more individualized than plain %max zones.
Which zone burns the most fat?
Zone 2 burns the highest percentage of calories from fat, but total fat loss depends on overall calorie balance, not the fuel mix during one session. Higher zones burn more total calories per minute. The practical answer: Zone 2 is the most sustainable, so you can accumulate far more weekly volume — and that's what moves body composition.
Why is my heart rate higher than the zones suggest?
Heat, humidity, caffeine, dehydration, poor sleep, stress, illness, and altitude all elevate heart rate at a given pace. Cardiac drift — HR climbing over a long session even at steady pace — is also normal. If the numbers consistently feel wrong, use the talk test to anchor each zone to perceived effort instead.
How often should I recalculate my zones?
Age-based max HR changes slowly, so recalculating once or twice a year is enough. If you use Karvonen zones, re-measure your resting heart rate every few months — a dropping resting HR is a sign of improving fitness and shifts your zones downward.