The most common way to calculate your maximum heart rate is to subtract your age from 220. A 40-year-old, for example, would have an estimated max of 180 beats per minute. This formula has been the standard for nearly four decades, but it comes with a significant margin of error, and newer alternatives may give you a more accurate number depending on your sex, fitness level, and goals.
The 220-Minus-Age Formula
The classic formula (max heart rate = 220 – age) was popularized by Fox and colleagues in the 1970s and quickly became the default in gyms, fitness trackers, and doctor’s offices. It’s simple and requires nothing beyond knowing how old you are. But “simple” and “accurate” aren’t the same thing.
Research spanning more than two decades has documented a standard error of 7 to 11 beats per minute with this formula. When researchers went back and reanalyzed the original data Fox used, they found the actual regression line produced a different equation entirely (roughly 215 minus 0.9 times age), with an error margin as high as 21 beats per minute. In practical terms, that means two healthy 45-year-olds could have true max heart rates that differ by 20 or more beats, yet the formula spits out the same number for both of them.
For casual exercisers who just want a rough sense of intensity, 220 minus age works fine. But if you’re using heart rate zones to structure training or assess cardiovascular fitness, that built-in error can throw off every zone you calculate from it.
A More Accurate Formula for Women
The 220-minus-age formula was derived almost entirely from studies of men. Research led by Dr. Martha Gulati established a separate formula for women: 206 minus 88 percent of your age. For a 40-year-old woman, that yields about 171 beats per minute, compared to 180 from the standard formula.
The difference matters beyond fitness tracking. Women have different physiologic responses to exercise, including differences in exercise capacity. When clinicians used the standard formula to evaluate women on stress tests, they were more likely to tell women they had a worse prognosis than they actually did. If you’re a woman using heart rate to guide workouts, the Gulati formula is a better starting point.
Another Alternative: The Tanaka Formula
A second widely cited update is 207 minus 0.7 times your age, sometimes called the Tanaka formula. Cleveland Clinic references this version as an option alongside the classic 220-minus-age calculation. For a 50-year-old, it gives 172 beats per minute instead of 170, a small difference at that age. The gap widens for younger and older adults. This formula was developed from a larger and more diverse dataset than the original Fox equation, so many exercise physiologists consider it a better estimate across the age spectrum.
How to Measure It Directly
Formulas estimate. If you want your actual max heart rate, you need to push your cardiovascular system to its ceiling and record the number. There are two main ways to do this: a clinical stress test or a field test you run yourself.
Clinical Stress Tests
In a clinical setting, the most common approach is a graded treadmill test. The standard Bruce protocol starts at a slow walking pace on a moderate incline and increases both speed and grade every three minutes. Stage 1 is 1.7 miles per hour at a 10% incline. By stage 3, you’re at 3.4 miles per hour on a 14% grade. The goal is to ramp up effort gradually until you physically can’t continue, at which point your recorded heart rate represents your true max. A modified version adds two easier warmup stages for people who need a gentler start.
These tests are typically done under medical supervision with continuous heart monitoring, which makes them the gold standard for accuracy and safety.
Field Tests
If you already have a baseline of fitness and a reliable heart rate monitor, you can approximate a max heart rate test on your own. One well-known protocol from sports medicine: run or bike up a hill for four to six minutes at a very hard effort, then sprint as hard as you can when you feel you’re near your limit. Check your heart rate monitor at that peak moment. That reading is your functional max.
A few caveats apply. You need to be healthy and already somewhat fit for this to be safe and valid. If you’re over 35 and new to exercise, getting medical clearance first is a reasonable step. You’ll also get a more reliable number if you repeat the test on a separate day and compare results, since hydration, sleep, and fatigue all influence your peak on any given attempt.
Why Beta-Blockers Change Everything
If you take beta-blockers (commonly prescribed for high blood pressure, anxiety, or heart rhythm issues), none of these formulas or tests will give you a useful max heart rate. Beta-blockers work by suppressing your heart rate response to exertion, so your heart physically cannot reach the ceiling it otherwise would. Harvard Health recommends that people on beta-blockers skip heart rate targets entirely and instead use a perceived exertion scale, rating how hard exercise feels on a scale of 1 to 10, to gauge workout intensity.
Turning Max Heart Rate Into Training Zones
Knowing your max heart rate is only useful if you apply it. The simplest method is to calculate percentages directly: 70% of a 180 max is 126 beats per minute. Most general fitness guidelines suggest moderate exercise falls between 50% and 70% of max, while vigorous exercise is 70% to 85%.
A more personalized approach uses something called heart rate reserve, which accounts for your resting heart rate. The math: subtract your resting heart rate from your max heart rate. That gap is your reserve. To find a target for a specific intensity, multiply the reserve by your desired percentage, then add your resting heart rate back on.
Here’s a concrete example. Say your max is 180 and your resting heart rate is 60. Your heart rate reserve is 120. If you want to train at 70% intensity, multiply 120 by 0.70 to get 84, then add your resting heart rate: 84 + 60 = 144 beats per minute. This method, known as the Karvonen formula, produces more individualized targets because two people with the same max but different resting heart rates will get different zones. Someone with a resting rate of 50 would get a higher target than someone resting at 70, reflecting the fitter person’s greater cardiovascular range. Cardiac rehab programs commonly use 60% to 80% of heart rate reserve to set exercise intensity, and the same approach works well for general fitness training.
Which Method Should You Use
For most people, 220 minus age is a reasonable starting point. If you’re a woman, the Gulati formula (206 minus 88% of age) is more accurate. If you’re an athlete building structured training plans, a field test with a heart rate monitor will give you a number that no formula can match. And if your estimated zones don’t feel right, meaning you feel like you’re barely working at what’s supposed to be 80%, or you’re gasping at 60%, that’s a strong signal your true max is different from what any equation predicts.