Calculator
What the Exercise Heart Rate Calculator does
Exercise Heart Rate Calculator: calculates Max HR, Fat-burn / easy low and Fat-burn / easy high from Age and Resting Heart Rate. Formula: Max HR ≈ 220 - age; target zone = resting + (max - resting) x intensity. Example: age 30 and resting heart rate 70 bpm gives max HR 190.
With Age and Resting Heart Rate entered, the Exercise Heart Rate Calculator works out 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 Exercise Heart Rate Calculator exists to take that particular chore off your hands.
The page holds your values in memory and forgets them the moment you close it.
Field definitions, the method, and a worked example from the default values are all set out further down the page.
What do the Exercise Heart Rate Calculator fields mean?
The Exercise Heart Rate 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 Exercise Heart Rate Calculator work?
The 220 - age rule has a standard deviation of roughly 10 to 12 bpm, so treat zones as a range rather than a threshold.
Validation runs before the calculation, which is why a mistyped value shows an error rather than a plausible-looking result.
Worked example
These are the values the Exercise Heart Rate 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). |
Heart rate during exercise
Heart rate during exercise is a proxy for intensity, but it lags behind actual effort by 30 to 60 seconds and is pushed around by heat, hydration and stress.
| Zone 1, recovery | 50 to 60% of reserve | conversational, all day pace |
|---|---|---|
| Zone 2, aerobic base | 60 to 70% | can hold a conversation |
| Zone 3, tempo | 70 to 80% | short sentences only |
| Zone 4, threshold | 80 to 90% | a few words at a time |
| Zone 5, maximum | 90 to 100% | no talking, minutes at most |
Worth knowing
- Cardiac drift raises heart rate by 5 to 10% over a long steady session at constant effort, mostly from dehydration and heat.
- The talk test tracks these zones well and needs no equipment or formula.
- Heat, altitude, caffeine, illness and poor sleep all raise heart rate at the same workload.
- Wrist optical sensors are noticeably less accurate than a chest strap during high-intensity or high-cadence work.
How to use it
- Type Age (10 to 90).
- Enter Resting Heart Rate in bpm (35 to 120).
- No submit step is needed; the output updates while you edit.
- Look at Max HR, Fat-burn / easy low, Fat-burn / easy high, Cardio zone high and What this means in the output 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
- This is a screening estimate, not a diagnosis.
- Body composition, ethnicity and age all shift what a "normal" result means.
- Batch work is not supported; each run handles one set of values.
- Garbage in, garbage out: confirm each figure means what you think it does before trusting the result.
Frequently asked questions
Enter Resting Heart Rate in bpm. Both the inputs and the result are explicitly labelled, so mixed units cannot slip through unnoticed.
Age accepts 10 to 90. Anything beyond those bounds is flagged rather than approximated.
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. Your browser is doing the computing, so we could not see the values even if we wanted to.
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.