The Target Heart Rate Zone Calculator maps five training intensity zones in beats per minute, based on age and, when entered, resting heart rate. Choose a maximum-heart-rate formula, and the tool returns each zone as a bpm range, using either a simple percentage of estimated maximum or the more personalized Karvonen heart-rate-reserve method.
Heart rate zones are coaching tools for structuring a workout, not a diagnostic reading. Every figure here is an estimate with real individual variation, and anyone with a heart condition, or anyone new to vigorous exercise, should get medical clearance before training by these zones.
Calculate your target heart rate zones
Target zones divide the range between resting and maximum heart rate into five bands, each associated with a different training purpose, from easy warm-up effort to maximum short-interval intensity.
| Zone | Percent of max or reserve | Label | Typical purpose |
|---|---|---|---|
| 1 | 50 to 60% | Very light | Warm-up, recovery |
| 2 | 60 to 70% | Light | Base endurance |
| 3 | 70 to 80% | Moderate | Aerobic fitness |
| 4 | 80 to 90% | Hard | Anaerobic threshold, performance |
| 5 | 90 to 100% | Maximum | Short intervals, peak effort |
Estimate your maximum heart rate
Maximum heart rate declines with age on average, though individuals vary widely around any formula's prediction. Three common estimates are available.
| Formula | Equation | Note |
|---|---|---|
| Fox | 220 − age | Common rule of thumb; scatter often ±10 to 12 bpm |
| Tanaka | 208 − 0.7 × age | Often tracks measured maxima more closely |
| Gulati | 206 − 0.88 × age | Derived specifically on women |
Worked example: a 40-year-old using each formula.
Tanaka: 208 − 0.7 × 40 = 208 − 28 = 180 bpm. Fox: 220 − 40 = 180 bpm (matches Tanaka at this specific age; the two diverge at other ages). Gulati: 206 − 0.88 × 40 = 206 − 35.2 ≈ 171 bpm.
Apply the Karvonen formula for personalized zones
The Karvonen method uses heart-rate reserve, the gap between maximum and resting heart rate, to personalize each zone rather than relying on a flat percentage of maximum alone.
target = ((maxHR − restingHR) × intensity) + restingHRWorked example: age 40, resting heart rate 60 bpm, using the Tanaka maximum of 180 bpm.
1. Calculate heart-rate reserve. 180 − 60 = 120 bpm.
2. Apply zone 3's lower bound (70% intensity). (120 × 0.70) + 60 = 84 + 60 = 144 bpm.
3. Apply zone 3's upper bound (80% intensity). (120 × 0.80) + 60 = 96 + 60 = 156 bpm.
So zone 3 for this profile runs from 144 to 156 bpm under the Karvonen method, generally a higher floor than a simple 70 to 80 percent of maximum alone would give (126 to 144 bpm), because Karvonen accounts for the fact that the heart never actually rests at zero bpm.
Measure resting heart rate accurately
Resting heart rate is best measured seated or lying down, after several quiet minutes, ideally in the morning before caffeine or any physical activity. A rushed or post-activity reading inflates the resting figure, which compresses the calculated reserve and pushes every Karvonen zone boundary higher than it should be.
Resting heart rate also changes with fitness level and health status, so rechecking it periodically keeps the zones current.
Choose between percentage-of-max and Karvonen
If resting heart rate is not entered, zones default to a simple percentage of estimated maximum heart rate, which is simpler but less personalized.
Entering a resting heart rate switches to the Karvonen method, which generally produces a narrower, more individualized zone range, especially useful for people whose resting heart rate is notably higher or lower than average for their age.
This is general information, not medical advice
Heart rate zones calculated here are coaching estimates for general training guidance. They are not a medical diagnosis or a clearance to exercise at any given intensity. Anyone with a diagnosed heart condition, anyone experiencing symptoms during exercise, or anyone new to vigorous physical activity should consult a doctor before training using calculated heart rate zones.
Frequently asked questions
How do you calculate target heart rate zones?
Estimate maximum heart rate from age using a formula such as Tanaka or Fox, then apply percentage ranges (50 to 100 percent) to define five zones, or use the Karvonen method with resting heart rate for a more personalized range.
What is the Karvonen formula?
Karvonen calculates a target heart rate using heart-rate reserve: target = ((max HR − resting HR) × intensity) + resting HR, where intensity is the zone's percentage as a decimal.
Which maximum heart rate formula is most accurate?
No single formula is exact for every individual. Tanaka (208 − 0.7 × age) often tracks measured maxima more closely across a wide age range than the simpler Fox formula (220 − age), but individual variation of ±10 to 12 bpm or more is common with any formula.
Why does Karvonen give higher zone numbers than percent-of-max?
Because Karvonen accounts for heart-rate reserve, the gap above resting heart rate rather than the gap above zero, which raises the effective floor of every zone, particularly for people with a lower resting heart rate.
What is zone 2 used for?
Zone 2 (60 to 70 percent) is commonly labeled for base endurance and is sometimes called a "fat burning" zone in consumer apps, though total calories burned and overall training effect still depend heavily on duration and individual fitness level, not the zone label alone.
How should I measure my resting heart rate?
Measure it seated or lying down after several quiet minutes, ideally in the morning before caffeine or exercise, for the most accurate and consistent reading.
Are these heart rate zones medical guidance?
No. They are general coaching estimates for training planning. Anyone with a heart condition or new to vigorous exercise should get medical clearance before training by calculated heart rate zones.
Summary
Heart rate training zones divide the range from resting to maximum heart rate into five bands, from very light recovery effort to maximum short-interval intensity, using either a percentage of estimated maximum or the more personalized Karvonen heart-rate-reserve method.
For a 40-year-old with a 60 bpm resting rate and a Tanaka maximum of 180 bpm, Karvonen zone 3 runs from 144 to 156 bpm, higher than the equivalent percent-of-max range, because Karvonen accounts for the heart never truly resting at zero.