Fitness

Heart rate zones

Calculate your 5 training heart rate zones from your age and optional resting heart rate.

Age (years)

Resting heart rate (bpm) optional

Enables Karvonen formula

Max HR override optional

100% private. All processing happens locally in your browser — no files or data are ever sent to a server.

How to use Heart rate zones

01 Fill in the required values using the fields provided
02 Results calculate automatically as you type
03 Copy or note the result — all calculations stay on your device

Frequently asked questions

Common questions about Heart rate zones.

Is Heart rate zones free to use?

Yes, Heart rate zones is completely free. No account, subscription, or payment is ever required — just open the page and start using it.

Does Heart rate zones upload my data to a server?

No. Heart rate zones runs entirely in your web browser using client-side JavaScript. Your files, text, and data never leave your device, making it 100% private.

Can I use Heart rate zones on my phone or tablet?

Yes. Heart rate zones is fully responsive and works on all modern smartphones, tablets, and desktop browsers without installing any app.

Are these results accurate enough to rely on?

Heart rate zones uses well-established formulas and provides accurate estimates for everyday use. For financial, medical, or legal decisions, always consult a qualified professional.

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About Heart rate zones

Training by heart rate zone allows precise control of exercise intensity and ensures you spend enough time in each physiological adaptation zone. The five standard zones are based on percentages of maximum heart rate (HRmax), estimated as 220 minus age. When a resting heart rate is provided, the Karvonen formula gives more individualised zone boundaries by using heart rate reserve (HRmax − resting HR). Zone 1 (50–60%) is active recovery; Zone 2 (60–70%) builds aerobic base and fat metabolism; Zone 3 (70–80%) improves aerobic capacity; Zone 4 (80–90%) develops lactate threshold; Zone 5 (90–100%) is maximum effort for peak performance.