Calculator
What the Fat Burning Zone Calculator does
Fat Burning Zone Calculator: calculates Max HR, Fat-burn / easy low and Fat-burn / easy high from Age and Resting Heart Rate. Example: age 30 and resting heart rate 70 bpm gives max HR 190.
The Fat Burning Zone Calculator turns Age and Resting Heart Rate into Max HR, Fat-burn / easy low and Fat-burn / easy high. Everything recomputes live, which makes it easy to test a few scenarios in a row.
Knowing how a figure is derived makes it much easier to interpret sensibly. The Fat Burning Zone Calculator exists to take that particular chore off your hands.
Nothing you enter about your body is sent anywhere or stored.
Everything needed to verify a result is further down: the fields, the method and one fully worked example.
What do the Fat Burning Zone Calculator fields mean?
The Fat Burning Zone Calculator uses 2 inputs. It opens with a complete example loaded, which is usually the quickest way to understand what a field means.
| Field | What to enter | Default |
|---|---|---|
| Age | accepts 10 to 90 | 30 |
| Resting Heart Rate | measured in bpm; accepts 35 to 120 | 70 |
How does the Fat Burning Zone Calculator work?
Each output is derived from the inputs above in a single pass; there is no hidden state carried between runs, so the same inputs always give the same calculation.
Inputs are validated before anything is computed, so a bad entry is reported rather than quietly producing a wrong answer.
Worked example
These are the values the Fat Burning Zone Calculator loads by default, and the result it produces from them. The numbers below come straight from the default inputs, so you can verify them against the live tool.
| Age | 30 |
|---|---|
| Resting Heart Rate | 70 bpm |
| Max HR | 190 |
|---|---|
| Fat-burn / easy low | 142 |
| Fat-burn / easy high | 154 |
| Cardio zone high | 166 |
| What this means | Max HR ≈ 190 bpm. Easy aerobic work often sits near 142 to 154 bpm (Karvonen method). |
How to use it
- Key in Age (10 to 90).
- Fill in Resting Heart Rate in bpm (35 to 120).
- There is nothing to click. The answer keeps pace with your edits.
- Read Max HR, Fat-burn / easy low, Fat-burn / easy high, Cardio zone high and What this means in the results panel.
- To keep the result, either copy the link or print the page. Both preserve what is on screen.
What this tool does not do
- Body composition, ethnicity and age all shift what a "normal" result means for an individual.
- Population-level formulas cannot account for medical conditions, medication or pregnancy.
- The tool answers exactly the question it is given; it cannot know the context around your numbers.
- A number that passes validation has been checked for plausibility, not for correctness.
Frequently asked questions
Enter Resting Heart Rate in bpm. Each field states its unit next to the input, and outputs are labelled the same way.
Age accepts 10 to 90. The range is enforced before the calculation runs, so a bad entry never reaches the formula.
With the values loaded when the page opens, max HR comes out as 190. Try changing one value. The answer refreshes without a page reload.
No. There is no account, no session and no storage. The values exist only while the tab is open.
It is free with no conditions: no sign-up, and no limit on how often you use it.
Accurate to the published method. Whether the published method suits your circumstances is a question for someone who knows your history.