The simplest way to estimate your max heart rate is to subtract your age from 220. A 35-year-old, for example, gets an estimated max of 185 beats per minute (bpm). But this quick formula can be off by 10 to 15 bpm in either direction, which is a big enough gap to throw off your training zones. More accurate formulas exist, and if precision matters to you, a field test or clinical stress test will get you closer to your true number.
The 220-Minus-Age Formula
This is the formula most people encounter first: max heart rate equals 220 minus your age. It was developed decades ago by Fox and colleagues and remains the default in gyms, fitness apps, and cardio machines. Its appeal is obvious: no equipment, no math beyond basic subtraction.
The problem is accuracy. Age alone accounts for roughly 35 to 80 percent of the variation in max heart rate from person to person, and studies report standard deviations of 10 to 12 bpm, with some recent data showing deviations as high as 14 to 15 bpm. That means two healthy 40-year-olds could have true max heart rates of 165 and 195 while both getting the same estimate of 180. If you’re using heart rate zones for serious training, that margin of error matters.
More Accurate Formulas
Researchers have developed alternatives that perform better for specific populations.
The Tanaka formula, based on a meta-analysis of over 18,000 subjects, calculates max heart rate as 208 minus 0.7 times your age. For a 45-year-old, that gives 176.5 bpm instead of the 175 you’d get from 220 minus age. The difference grows at the extremes of age, where the simpler formula tends to overestimate max heart rate in older adults and underestimate it in younger ones.
For women specifically, research from the American College of Cardiology found that the 220-minus-age formula was based on studies that included few female participants. Heart rate declines more gradually with age in women than in men, so the old formula overestimates peak heart rate in younger women and underestimates it in older women. The ACC study produced sex-specific formulas: for women aged 40 to 89, max heart rate equals 200 minus 67 percent of age. For men, it’s 216 minus 93 percent of age. A 50-year-old woman would get 166.5 bpm from this formula versus 170 from the standard one.
No single formula is perfect for everyone, but choosing one designed for your sex and backed by a larger study population will generally get you closer to your real number.
Finding Your True Max With a Field Test
If you want a number based on your actual body rather than a population average, a field test is the most accessible option. You’ll need a heart rate monitor (a chest strap is more reliable than a wrist sensor at high intensities) and ideally a training partner for safety.
A common protocol uses hill repeats:
- Warm up for 15 minutes on flat ground, gradually building to your normal training pace.
- Find a hill that takes at least two minutes to climb.
- Run up the hill once, building to a pace you estimate you could sustain for about 20 minutes. You don’t need to actually run for 20 minutes. Just reach that effort level.
- Jog back down to recover.
- Run up the hill again at a noticeably faster pace, pushing toward your hardest sustainable effort.
- Check your heart rate monitor at the top. The highest reading from this second effort is a close approximation of your max heart rate.
This test requires you to be comfortable with high-intensity exercise. If you haven’t been training regularly, start with the estimation formulas and revisit the idea of a field test once you’ve built a fitness base.
The Clinical Stress Test
A graded exercise test in a medical setting is the gold standard. You walk on a treadmill or pedal a stationary bike while the speed, incline, or resistance increases in stages. Throughout the test, clinicians monitor your heart rate, rhythm, blood pressure, and an electrocardiogram in real time. You may also breathe into a tube so they can measure oxygen consumption. The test continues until you reach exhaustion or a clinical reason to stop.
This approach gives you a precise, individually measured max heart rate. It’s typically ordered for medical reasons (evaluating chest pain, heart disease risk, or exercise capacity after a cardiac event), but athletes and serious recreational exercisers sometimes request one through a sports medicine clinic.
Why Your Max Heart Rate Might Not Match the Formula
Beyond normal individual variation, several factors can shift your achievable max heart rate away from any formula’s prediction.
Medications: Beta-blockers, commonly prescribed for high blood pressure and certain heart conditions, slow heart rate and prevent it from climbing the way it normally would during exercise. According to the Mayo Clinic, you may never reach your predicted target heart rate while on a beta-blocker, no matter how hard you push. If you take one, the standard formulas aren’t useful. A clinical stress test or a perceived exertion scale (rating your effort on a 1-to-10 or 6-to-20 scale) is a better guide for training intensity.
Altitude: At high elevations, your heart rate runs higher during moderate exercise but your achievable maximum actually drops. Research published in Circulation found that at roughly 7,600 meters (about 25,000 feet), max heart rate was reduced by 20 percent compared to sea level. You don’t need to be on Everest to notice the effect. Even moderate altitudes of 1,500 to 2,500 meters can shift your max down by a few beats.
Heat: Exercising in hot conditions raises heart rate at any given intensity because your cardiovascular system works harder to cool you. This can make submaximal efforts feel like you’re near your ceiling, but your true physiological max doesn’t change much. The practical takeaway: on very hot days, your heart rate zones may feel shifted upward even though your max hasn’t actually moved.
Turning Max Heart Rate Into Training Zones
Knowing your max heart rate is useful mainly because it lets you set training zones. The simplest method is to calculate percentages of your max. A common breakdown puts easy aerobic exercise at 60 to 70 percent, moderate effort at 70 to 80 percent, and high intensity at 80 to 90 percent.
A more individualized approach uses heart rate reserve, sometimes called the Karvonen method. Heart rate reserve is your max heart rate minus your resting heart rate. To find a target zone, you multiply your heart rate reserve by the desired percentage and then add your resting heart rate back in. For example, if your max is 185 and your resting heart rate is 60, your heart rate reserve is 125. To train at 70 percent intensity: 125 times 0.70 equals 87.5, plus your resting heart rate of 60, gives a target of about 148 bpm.
This method accounts for your baseline fitness level. Two people with the same max heart rate but different resting heart rates will get different target zones, which more accurately reflects the actual demand on their cardiovascular systems. To measure your resting heart rate, check your pulse first thing in the morning before getting out of bed, and average several days for a reliable number.