Heart Rate Zone Calculator
Calculate target cardio training zones (Fat Burn, Aerobic, Peak).
This heart rate zone calculator estimates your maximum heart rate and breaks it into training zones (fat burn, aerobic, and peak/anaerobic) using the Karvonen formula, which factors in your resting heart rate for a more personalized result than age alone.
Enter your age and resting heart rate, and the calculator returns your target heart rate ranges for each training zone.
Worked Calculation Examples
| Scenario | Result | Calculation Step |
|---|---|---|
| 30-year-old, resting HR 65 bpm, 70% intensity (aerobic zone) | ≈153 bpm target | Max HR = 220 − 30 = 190. HRR = 190 − 65 = 125. Target = (125 × 0.70) + 65 = 87.5 + 65 = 152.5 ≈ 153 bpm. |
| 45-year-old, resting HR 72 bpm, 60% intensity (fat-burn zone) | ≈134 bpm target | Max HR = 220 − 45 = 175. HRR = 175 − 72 = 103. Target = (103 × 0.60) + 72 = 61.8 + 72 = 133.8 ≈ 134 bpm. |
The Karvonen Formula
The Karvonen method calculates target heart rate as: ((max HR - resting HR) x intensity%) + resting HR. Using heart rate reserve (the gap between max and resting heart rate) rather than max heart rate alone accounts for individual fitness differences - two people with the same max heart rate can have very different resting rates and fitness levels. Finnish physiologist Martti Karvonen introduced this method in a 1957 study after finding that training zones based on heart rate reserve better matched an individual's actual aerobic fitness level than max heart rate alone, making it possible to prescribe comparable relative-intensity workouts to people with very different baseline fitness.
What Each Zone Is For
Lower-intensity zones (roughly 50-60% of heart rate reserve) are associated with fat-burning and easy recovery efforts, moderate zones (60-70%) build aerobic base fitness, and higher zones (70-85%+) improve cardiovascular capacity and performance. Training across different zones on different days is a common structure for balanced cardio programming.
Common Mistakes with Heart Rate Zones
The most common mistake is measuring resting heart rate after getting up and moving around rather than immediately upon waking, which inflates the number and skews every zone calculated from it. Another is using the blunt 220-minus-age formula directly as a personal maximum rather than as a population average - actual max heart rate for people of the same age can vary by 10-20 beats per minute in either direction. A third is training almost exclusively in one zone (usually too hard, too often) rather than varying intensity across a week, which most cardio programming guidance recommends against.
Sources & References
The Karvonen method comes from Martti Karvonen's 1957 study on heart rate and training intensity, published in the Annales Medicinae Experimentalis et Biologiae Fenniae. The 220-minus-age maximum heart rate estimate is a widely used population-average formula rather than a laboratory-measured value for any individual; the American Heart Association publishes target zone ranges consistent with the percentages used here.
How to Use the Heart Rate Zone Calculator
- Open the Heart Rate Zone Calculator and enter the values requested in the input fields.
- Check the units, percentages, dates, or time periods before reading the answer.
- Review the instant result and adjust any value to compare another scenario.
- Use the formula, example, and FAQs below to understand how the heart rate zone calculator works.
Frequently Asked Questions
How do I calculate my heart rate zones?
Estimate your maximum heart rate (commonly 220 minus age), then apply the Karvonen formula using your resting heart rate to find target ranges for each training zone.
What is the Karvonen formula?
It calculates target heart rate as ((max heart rate - resting heart rate) x intensity percentage) + resting heart rate, giving a more personalized target than max heart rate alone.
What heart rate zone burns the most fat?
Lower-intensity zones (roughly 50-60% of heart rate reserve) are generally associated with the highest percentage of calories from fat, though higher-intensity training burns more total calories overall.
How do I use this heart rate zone calculator?
Enter the known values, review the units or settings, and the calculator updates the result instantly. The formula and example on this page show how the answer is produced.
What does the Heart Rate Zone Calculator calculate?
Calculate target cardio training zones (Fat Burn, Aerobic, Peak). It is designed for fast browser-based calculations without sign-up, downloads, or manual spreadsheet setup.
What formula does this heart rate zone use?
The formula is: Target HR = [(Max HR − Resting HR) × Intensity%] + Resting HR, where Max HR = 220 − Age. Max HR is the age-based estimate of maximum heart rate. Resting HR is your heart rate measured at complete rest, ideally taken first thing in the morning before getting out of bed. Subtracting the two gives your Heart Rate Reserve (HRR) - the usable range between resting and maximum effort. Multiplying HRR by a target intensity percentage (typically 50-85%) and adding back the resting HR gives a target heart rate that's personalized to your own fitness baseline, not just your age.
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Last updated: September 29, 2026.