The most common way to estimate your maximum heart rate is to subtract your age from 220. A 40-year-old would get 180 beats per minute. It’s simple, widely used, and printed on cardio machines everywhere, but it can be off by a significant margin, especially as you get older. Several better formulas exist, and if accuracy matters for your training, you can measure it directly.
The 220-Minus-Age Formula and Its Limits
The classic formula, 220 minus your age, has been the default for nearly four decades. It gives you a single number in seconds, which is why it stuck. The problem is that it was never designed to be precise for individuals. It’s a rough population average with a standard deviation wide enough that your true max could be 10 to 12 beats higher or lower than the estimate, even in younger adults.
The inaccuracy gets worse with age. According to researchers at the Norwegian University of Science and Technology, the 220-minus-age formula can underestimate max heart rate by up to 40 beats per minute in older adults. It starts drifting noticeably around age 30 to 40 and becomes increasingly unreliable from there. If you’re 60 and the formula says your max is 160, your actual max could be closer to 175 or even higher. That matters if you’re basing your training zones on it.
A More Accurate General Formula
A large meta-analysis published in the Journal of the American College of Cardiology produced a better equation: 208 minus 0.7 times your age. The researchers confirmed this by analyzing 351 studies involving nearly 19,000 subjects, then validated it in a separate lab-based study that produced a nearly identical result (209 minus 0.7 times age).
For a 40-year-old, this gives 180, the same as the old formula. But the two equations diverge as age increases. At 60, the old formula gives 160 while the updated one gives 166. At 70, the gap widens further: 150 versus 159. The underlying biology here is straightforward. Your heart’s intrinsic pacemaker slows by roughly 0.7 beats per minute for each year of life, independent of fitness level or lifestyle. This decline happens even when the nervous system’s influence on heart rate is completely blocked, which tells us it’s a structural change in the heart itself, not a training issue you can reverse.
Why Women Need a Different Formula
Both the classic and updated formulas were developed primarily from studies of men. Research from the St. James Women Take Heart Project, which tracked 5,437 healthy women aged 35 and older, found that women reach a lower peak heart rate than men of the same age and that the decline follows a different curve.
The formula for women: 206 minus 88 percent of your age. A 50-year-old woman would calculate 206 minus 44, giving a max of 162. The old formula would have predicted 170. That eight-beat gap has real consequences. Using the male-derived formula, clinicians were more likely to tell women they had a worse prognosis than they actually did, because women appeared to be “underperforming” against a target that was never accurate for them. On the exercise side, many women couldn’t hit their prescribed target heart rate zones, not because they were unfit, but because the zones were wrong.
How to Measure It Directly
Formulas estimate a population average. If you want your actual number, you need to push yourself to true maximal effort and record what happens. The most controlled way is a graded exercise test in a clinical or sports-performance lab, where you run on a treadmill or pedal a stationary bike at progressively harder intensities until you physically cannot continue. A technician monitors your heart with electrodes, giving you a precise reading.
If a lab test isn’t practical, a field test can get you close. One common approach is a series of hard uphill runs. After a thorough warmup of at least 15 minutes, run up a steep hill at near-maximum effort for two to three minutes, jog back down to recover, and repeat three times. On the final repeat, push as hard as you can for the last 60 seconds. The highest heart rate you see during that final effort is a reasonable approximation of your max. You need a chest strap or reliable wrist monitor to capture the number.
A few things will prevent you from hitting a true max on any given day. If you’re dehydrated, sleep-deprived, or at the tail end of a hard training block, your body may quit before your heart reaches its ceiling. Testing when you’re rested and well-fueled gives the most accurate result.
How Reliable Is Your Wrist Monitor?
Most smartwatches and fitness bands use optical sensors that shine light through your skin to detect blood flow. These work well at low and moderate intensities, but accuracy drops as your heart rate climbs. A study testing 16 commercial wrist-based monitors found that error rates increased consistently at higher intensities, with several popular devices failing to meet validation criteria above 160 beats per minute.
Not all devices are equal, though. Apple Watch models (particularly the Ultra) maintained very low error rates even during high-intensity interval training, with less than 1% measurement error at peak effort. Several Garmin and Polar models, by contrast, showed errors of 7% or more at high intensities, meaning a reading of 180 could actually be 167 or 193. If you’re using max heart rate to set training zones, that kind of error cascades through every workout.
A chest strap that reads electrical signals from your heart remains the gold standard for personal use. If you’re relying on a wrist sensor, check whether your specific model has been validated at high intensities before trusting it for max heart rate testing.
Factors That Change Your Max
Your maximum heart rate is mostly genetic and age-determined. Two people the same age can have max heart rates 20 beats apart, and neither number indicates better fitness. Fitness affects your resting heart rate and how efficiently your heart pumps at submaximal effort, but it doesn’t meaningfully raise or lower your ceiling.
Altitude does lower it. Studies conducted at elevations ranging from about 3,000 to nearly 9,000 meters consistently show that max heart rate drops as altitude increases. The mechanism involves reduced oxygen availability limiting how hard the heart can work. If you’ve moved to a mountain town or are training at elevation, your max will be lower than it was at sea level.
Medications can also change the picture entirely. Beta-blockers, commonly prescribed for high blood pressure and heart conditions, directly suppress heart rate. If you take one, formula-based max heart rate calculations won’t apply to you. A more practical approach is using perceived exertion, essentially rating how hard you feel you’re working on a scale of 1 to 10, to guide exercise intensity instead of chasing a heart rate number your medication won’t let you reach.
Putting the Number to Use
The reason most people want their max heart rate is to calculate training zones. These are typically expressed as percentages of your max. A common framework breaks it down like this:
- 50 to 60%: Light activity, warmup, recovery
- 60 to 70%: Easy aerobic exercise, fat oxidation emphasis
- 70 to 80%: Moderate aerobic training, the core of most endurance work
- 80 to 90%: Hard effort, threshold training
- 90 to 100%: Near-maximal, short intervals only
If your estimated max is 185 and your actual max is 175, every zone you calculate will be shifted upward by about 5 to 6 beats. That means your “easy” runs are actually moderate, your threshold work creeps into near-max territory, and you accumulate more fatigue than intended. This is the most common practical consequence of using an inaccurate max heart rate: chronic overtraining disguised as following a plan.
For most recreational exercisers, the updated formula (208 minus 0.7 times age) is a reasonable starting point. If you’re a woman, use 206 minus 88% of your age. If the zones feel consistently wrong (you can’t hold a conversation at what should be an easy pace, or “hard” efforts feel moderate), your estimate is probably off, and a field test is worth the effort.