Calculator
What the Heart Rate Calculator does
Heart Rate Calculator: calculates Est. Max HR, Fat Burn Low and Fat Burn High from Your Age and Resting Heart Rate. Formula: Max HR ≈ 220 - age; target zone = resting + (max - resting) x intensity. Example: your age 30 years and resting heart rate 70 bpm gives est. max HR 190.
Point it at Your Age and Resting Heart Rate and it returns Est. Max HR, Fat Burn Low and Fat Burn High. You can nudge a single number and watch the effect straight away.
Most people who open the Heart Rate Calculator are someone starting a new plan. A single number is most useful as a trend over time rather than a one-off judgement.
There is no back end here. The calculation runs where you are sitting, not on a server somewhere.
The sections that follow cover the fields, the method, and one full example computed from the defaults.
What do the Heart Rate Calculator fields mean?
The Heart Rate Calculator uses 2 inputs. Pre-filled inputs double as documentation: each one shows what a reasonable value looks like.
| Field | What to enter | Default |
|---|---|---|
| Your Age | measured in years | 30 |
| Resting Heart Rate | measured in bpm | 70 |
How does the 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.
The tool refuses to guess: if a value is missing or impossible, it says so.
Worked example
These are the values the Heart Rate Calculator loads by default, and the result it produces from them. This is the worked example the page starts from, reproduced here so you can check the arithmetic.
| Your Age | 30 years |
|---|---|
| Resting Heart Rate | 70 bpm |
| Est. Max HR | 190 |
|---|---|
| Fat Burn Low | 130 |
| Fat Burn High | 154 |
| Cardio Low | 154 |
| Cardio High | 172 |
| What this means | Fat-burn zone ≈ 130 to 154 bpm. Cardio zone ≈ 154 to 172 bpm (Karvonen method). |
Heart rate reference
Three numbers between them describe cardiovascular effort: resting, maximum, and where you are working between them.
| Maximum (Tanaka) | 208 − 0.7 × age | age 40 → 180 bpm |
|---|---|---|
| Reserve | max − resting | 180 − 60 = 120 bpm |
| Target (Karvonen) | resting + reserve × intensity | 60 + 120 × 0.7 = 144 bpm |
| Normal resting adult | 60 to 100 bpm | lower with training |
Worth knowing
- All maximum heart rate formulas carry roughly ±10 to 12 bpm of individual variation.
- Resting rate responds to training over weeks, which makes it a useful long-run fitness indicator.
- Medication, particularly beta blockers, invalidates these estimates entirely.
- This is general information and not medical advice. Persistent unexplained changes should be discussed with a doctor.
How to use it
- Enter Your Age in years.
- Set Resting Heart Rate in bpm.
- Because it recalculates as you type, you can dial a value in rather than guessing and re-running.
- You get Est. Max HR, Fat Burn Low, Fat Burn High, Cardio Low, Cardio High and What this means back.
- Copy Link puts the current inputs in the URL, so bookmarking it brings the same numbers back.
What this tool does not do
- Body composition, ethnicity and age all shift what a "normal" result means.
- These formulas come from population averages and cannot account for your medical history.
- It cannot detect a typo that happens to fall inside the valid range.
- Results are only as good as the inputs. Check your units before reading anything into the output.
Frequently asked questions
Enter Your Age in years and Resting Heart Rate in bpm. Look for the unit beside each label; the result is reported in a stated unit as well.
With the values loaded when the page opens, est. max HR comes out as 190. The figure is derived from the inputs above, so it updates whenever they do.
Nothing leaves your machine. The only network traffic is loading the page itself.
No. There is no account, no usage cap and no trial period. The site is funded by advertising rather than by charging for the tools.
The number is exact; its meaning is approximate. Two people with identical results can be in genuinely different situations, which is why this is a screening tool rather than a diagnostic one.