Cardio

Heart Rate Zone Calculator

Five training zones (Z1 recovery → Z5 anaerobic). Pick the simple max-HR method, or the more accurate Karvonen reserve method that uses your resting HR.

Your numbers

The two methods

Percentage of Max HR

Max HR (Tanaka) = 208 − 0.7 × age Zone 1: 50–60% of max Zone 2: 60–70% Zone 3: 70–80% Zone 4: 80–90% Zone 5: 90–100%

Karvonen / Heart Rate Reserve (more accurate)

HRR = max HR − resting HR Zone X bpm = (HRR × Zone%) + resting HR

Karvonen accounts for fitness level via your resting HR — a fitter athlete with a low resting HR gets a wider, more accurate range.

What each zone is for

Z1 (50–60%) Active recovery, warmup, cooldown
Z2 (60–70%) Aerobic base — the famous "zone 2" cardio
Z3 (70–80%) Tempo work, sustained efforts
Z4 (80–90%) Lactate threshold intervals
Z5 (90–100%) VO2 max / anaerobic intervals

FAQ

How accurate is the 220 − age formula?

Not very. It can be off by ±10–20 bpm. We use Tanaka (208 − 0.7 × age), which is more accurate for adults across the age range.

How do I find my real max HR?

An all-out 4-minute hill effort or a max-HR test under supervision. Or use a heart-rate monitor during a hard race.

What's "Zone 2" and why is it popular?

The aerobic-base zone — easy enough that you can hold a conversation. Builds mitochondrial density and fat oxidation. Most endurance coaches recommend 80% of training volume in Z2.

Coach your cardio with real data.

FitBear pulls live HR from your Apple Watch and grades whether you actually trained in zone.

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