Heart rate reserve calculator

What is the Karvonen formula?

Target heart rate = (max heart rate − resting heart rate) × intensity + resting heart rate. The difference between max and resting is your heart rate reserve.

Example

Age 30 with a resting rate of 60: max 220 − 30 = 190, reserve 130. At 50% intensity, 130 × 0.5 + 60 = 125 beats per minute; at 70%, 151.

What intensity should I use?

ACSM’s position stand (Garber et al., 2011) classes 40–59% of heart rate reserve as moderate and 60–89% as vigorous; below 30% is very light.

Which max heart rate formula is better?

220 − age is the common estimate; Tanaka and colleagues (2001) found 208 − 0.7 × age fits healthy adults better and does not underestimate it in older people. Both are estimates.

How do I measure my resting heart rate?

Count your pulse for a full minute after waking, before getting up, on a few mornings and average them.

How do I find my percent of heart rate reserve during exercise?

Subtract your resting rate from your current heart rate and divide by your reserve: (heart rate − resting) ÷ (max − resting). At age 30 with a resting rate of 60 (max 190), a reading of 140 beats per minute is (140 − 60) ÷ 130 = 61.5% of reserve, which falls in ACSM's vigorous range of 60–89%.

Why does this calculator give different numbers from others?

Two things differ between calculators: the formula for maximum heart rate (220 − age or 208 − 0.7 × age), and whether the percentage is taken of the maximum or of the reserve. Seventy percent of the maximum is a lower-effort number than 70% of the reserve for the same person, as the example below shows.

How the Karvonen method works

The method starts from the heart rate reserve, the gap between the maximum and the resting heart rate. Target = reserve × intensity + resting. Because the resting rate is added back, two people of the same age with different fitness get different targets, which a percent of maximum alone does not show. In ACSM's position stand (Garber and others, 2011) the intensity bands are given in percent of heart rate reserve, and that is the scale used here: below 30% very light, 30–39% light, 40–59% moderate, 60–89% vigorous and 90% or more near-maximal to maximal.

Worked example: two ways to estimate the maximum

Take a 60-year-old with a resting rate of 70. With 220 − age, the maximum is 160 and the reserve is 90; at 60% of reserve the target is 124.0 beats per minute. With 208 − 0.7 × age (Tanaka and colleagues, 2001), the maximum is 166.0, the reserve is 96.0, and the same 60% gives 127.6. The two estimates differ by about 4 beats per minute here, The two formulas give the same maximum at age 40; after that, the Tanaka line falls more slowly, so the gap widens with age. Neither is a measurement: an individual's true maximum can sit well away from either formula.

Mistakes to avoid

Do not apply a percent of reserve to the maximum or the other way around. For a 30-year-old with a resting rate of 60, 70% of the maximum is 133 beats per minute, but 70% of the reserve is 151, a difference of 18 beats per minute.

Measure the resting rate properly: after waking, lying down, for a full minute, over several mornings. A rate taken after coffee, stress or a poor night is higher than the true resting one, which pushes every target up. Some medicines, such as beta blockers, lower the heart rate during exercise, so the formulas may not apply; ask your doctor which targets suit you.

Sources: Garber CE and others, “Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness,” Medicine & Science in Sports & Exercise, 2011 (ACSM position stand), for the intensity bands; Tanaka H, Monahan KD, Seals DR, “Age-predicted maximal heart rate revisited,” Journal of the American College of Cardiology, 2001. Related tool: target heart rate calculator.

For general information only — not medical advice. Talk with your doctor or another health professional about your own health. How we check our calculators.