Target Heart Rate Zone Calculator
A target heart rate zone is the band of beats per minute that corresponds to a chosen training intensity. The Karvonen method calculates it from your heart rate reserve, the difference between your maximum and resting heart rates, which makes the zone more individual than a flat percentage of maximum. This calculator takes your maximum heart rate, resting heart rate, and a lower and upper intensity fraction, then returns the bottom and top of your target zone along with your heart rate reserve. Enter a measured maximum if you have one; otherwise an age-based estimate works as a starting point. The result is general fitness guidance, not medical advice.
Karvonen target heart rate formula
heart rate reserve = maximum HR - resting HR
target HR = heart rate reserve * intensity fraction + resting HR
lower bound uses the lower intensity; upper bound uses the upper intensity
midpoint = (lower bound + upper bound) / 2
Worked example: maximum 190, resting 60 gives reserve 130. At 60 percent the lower bound is 130 * 0.6 + 60 = 138 bpm; at 80 percent the upper bound is 130 * 0.8 + 60 = 164 bpm.
Heart rate zone notes
- Karvonen uses heart rate reserve, individualising the zone to your resting heart rate.
- Moderate activity is roughly 50 to 70 percent and vigorous roughly 70 to 85 percent of maximum.
- Enter a measured maximum heart rate where possible; age formulas are only estimates.
- Medications and conditions can change heart rate response.
- This is general fitness guidance, not medical advice.
Target heart rate: frequently asked questions
What is the Karvonen formula?
The Karvonen method sets target heart rate using heart rate reserve, the gap between maximum and resting heart rate. Target heart rate equals (maximum heart rate minus resting heart rate) times the intensity fraction, plus resting heart rate. It personalises the zone to your resting heart rate rather than using a flat percentage of maximum.
How do I estimate maximum heart rate?
A common rough estimate is 220 minus age, but this is only an approximation and individuals vary widely. This calculator takes maximum heart rate as a user-editable input so you can enter a measured value from a maximal test if you have one, or an age-based estimate if you do not.
What intensity should I train at?
The American Heart Association describes moderate-intensity activity at roughly 50 to 70 percent and vigorous activity at roughly 70 to 85 percent of maximum heart rate. With the Karvonen method these zones are expressed as a fraction of heart rate reserve. Enter the lower and upper intensity fractions to see your zone.
Why use heart rate reserve instead of percent of max?
A flat percentage of maximum heart rate ignores how fit your heart is at rest. Heart rate reserve accounts for resting heart rate, so two people with the same maximum but different resting rates get different, more individualised target zones.
Is a target heart rate zone safe for everyone?
Target zones are general fitness guidance, not medical advice. Some medications and health conditions change heart rate response. If you have a heart condition or take medication that affects heart rate, consult a clinician before using a target zone to guide exercise.
Official sources
- American Heart Association: Target heart rates chart.
- U.S. Centers for Disease Control and Prevention: Physical activity basics.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.