What is the difference between Karvonen and percentage of max?

The percentage-of-max method takes simple fractions of your maximum heart rate. The Karvonen method uses your heart-rate reserve (max minus resting), which accounts for individual fitness and gives more personalised zones, especially for the lower zones.

Why use 208 minus 0.7 times age instead of 220 minus age?

The Tanaka formula (208 − 0.7 × age, 2001) fits large population data better than the older 220 − age rule, which tends to overestimate for young people and underestimate for older people.

Is my data sent anywhere?

No. Every calculation runs in your browser and nothing is uploaded.

Which zone is the fat-burning zone?

Zone 2, roughly 60–70% intensity, is commonly called the fat-burning zone because a higher share of energy comes from fat. Total calorie burn is still higher in harder zones, so it is best for long, easy endurance work.

What heart rate is the cardio or aerobic zone?

Zone 3, about 70–80% intensity, is the moderate aerobic zone that builds cardiovascular fitness. Enter your age and resting heart rate to see the exact bpm range for you.

How do I find my resting heart rate?

Measure your pulse for one minute first thing in the morning before getting up, ideally averaged over a few days. A typical resting heart rate for adults is 60–100 bpm; fitter people tend to be lower.

Should I rely on these numbers for medical decisions?

No. These are population estimates for training guidance only. If you have a heart condition or take medication that affects heart rate, consult a doctor for personalised targets.

Target Heart Rate Zone Calculator

Target heart rate zone calculator

Training in the right heart-rate zone matches your effort to your goal — recovery, fat-burning, aerobic base, threshold, or peak performance. This calculator turns your age (and optionally your resting pulse) into all five training zones expressed in beats per minute, so you know what to aim for on a watch or chest strap.

How it works

Maximum heart rate is estimated with the Tanaka formula, which fits population data better than the older 220 − age rule:

HRmax = 208 − 0.7 × age

You then choose how the zone targets are built:

% of max HR: target = intensity% × HRmax. Simpler, no resting pulse needed.
Karvonen (heart-rate reserve): target = restingHR + intensity% × (HRmax − restingHR). The reserve (HRmax minus resting) accounts for your fitness, so it personalises the lower zones in particular.

Zone	Intensity	Purpose
1 — Very light	50–60%	Warm-up, recovery
2 — Light	60–70%	Endurance base (fat burn)
3 — Moderate	70–80%	Aerobic / cardio fitness
4 — Hard	80–90%	Anaerobic / performance
5 — Maximum	90–100%	Short intervals

Example

A 30-year-old gives HRmax = 208 − 0.7 × 30 = 187 bpm. Using Karvonen with a resting heart rate of 60 bpm, the heart-rate reserve is 187 − 60 = 127 bpm. The bottom of Zone 3 (70%) is 60 + 0.70 × 127 ≈ 149 bpm, and the top (80%) is 60 + 0.80 × 127 ≈ 162 bpm.

Everything runs in your browser — nothing is uploaded.