# Fat Burning Zone Calculator

URL: https://speedycalculator.com/calculators/sports/fat-burning-zone/
Last updated: 2026-10-30

> The fat burning zone calculator finds your fat-burning heart rate range three ways – 60–80% of maximum heart rate, the Zoladz method and the Karvonen (heart rate reserve) method – from your age (or measured maximum) and resting heart rate.

## Inputs

- Age (years)
- Measured maximum heart rate (0 = estimate)
- Resting heart rate (bpm)

## Results

- Maximum heart rate
- Heart rate reserve
- Zone (60–80% of max)
- up to
- Zoladz method from
- Zoladz method up to
- Karvonen method from
- Karvonen method up to

## Formula

```
MHR = 220 − age · Zone: 60–80% of MHR · Zoladz: MHR − 50 ± 5 to MHR − 40 ± 5 · Karvonen: (MHR − RHR) × 60–80% + RHR
```

## Explanation

At moderate intensity your body gets a large share of its energy from fat. That "fat-burning zone" is useful for long, comfortable sessions – though total calories burned, not the fuel mix, decides fat loss.

### How to use the Fat Burning Zone Calculator

- **Age (years)**
- **Measured maximum heart rate (0 = estimate)**
- **Resting heart rate (bpm)**

Results update as you type, every field has its own unit menu, and everything is calculated in your browser.

### How it works

Enter your age or measured maximum heart rate, and your resting heart rate.

### Inputs explained

FieldWhat to enterAge (years)A numberMeasured maximum heart rate (0 = estimate)A numberResting heart rate (bpm)A number

### What each result means

- **Heart rate reserve** = [Maximum heart rate] - [Resting heart rate (bpm)]
- **Zone (60–80% of max)** = round(0.6×[Maximum heart rate])
- **up to** = round(0.8×[Maximum heart rate])
- **Zoladz method from** = [Maximum heart rate] - 55
- **Zoladz method up to** = [Maximum heart rate] - 35
- **Karvonen method from** = round(0.6×([Maximum heart rate] - [Resting heart rate (bpm)]) + [Resting heart rate (bpm)])
- **Karvonen method up to** = round(0.8×([Maximum heart rate] - [Resting heart rate (bpm)]) + [Resting heart rate (bpm)])

### Example values

How the main result changes when **Age** changes and everything else stays at the example values above:

Age (years)Karvonen method from (bpm)17.514826.251423513743.7513252.512770116

## Worked example

Inputs — Age (years): 35; Measured maximum heart rate (0 = estimate): 0; Resting heart rate (bpm): 65.

Results — Maximum heart rate = 185 bpm; Heart rate reserve = 120 bpm; Zone (60–80% of max) = 111 bpm; up to = 148 bpm; Zoladz method from = 130 bpm; Zoladz method up to = 150 bpm; **Karvonen method from = 137 bpm**; Karvonen method up to = 161 bpm.

## Key terms

- **Heart rate reserve**: Maximum minus resting heart rate.

## FAQ

**Does the fat-burning zone burn more fat?**
It burns a higher share of fat, but harder exercise can burn more total calories.

**Which method is best?**
Karvonen, because it uses your resting heart rate.

**How do I measure resting heart rate?**
Count your pulse for 60 s in the morning before getting up.

**Is 220 − age accurate?**
It can be off by ±10–12 bpm; a measured maximum is better.


## Sources

- [American Heart Association – Target heart rates](https://www.heart.org/en/healthy-living/fitness/fitness-basics/target-heart-rates)
- [ACSM's Guidelines for Exercise Testing and Prescription](https://www.acsm.org/education-resources/books/guidelines-exercise-testing-prescription)