The simplest way to find your maximum heart rate is to subtract your age from 220. A 40-year-old, for example, would get an estimated max of 180 beats per minute. This formula has been the default for nearly four decades, but it has a margin of error that can be off by 10 to 12 beats in either direction. More accurate options exist, from updated formulas to field tests you can do yourself.
The Standard Formulas
The classic formula, known as the Fox formula, is straightforward: 220 minus your age. It’s printed on gym posters and built into most cardio machines. But it was derived from studies with limited populations and tends to overestimate max heart rate in younger adults while underestimating it in older ones.
A more refined version, sometimes called the Tanaka formula, adjusts for this: 208 minus 0.7 times your age. For a 40-year-old, that gives 180. For a 60-year-old, it gives 166 instead of the 160 you’d get from the Fox formula. The difference grows with age, which matters if you’re using heart rate zones to guide your training. Neither formula accounts for individual fitness level, genetics, or medications, so treat any result as a starting point rather than a precise number.
Why Women Get Different Results
Both of those formulas were developed primarily from studies of men. Research from the St. James Women Take Heart Project, which studied 5,437 healthy women ages 35 and older, found that women’s max heart rate declines with age at a different rate. The formula that came out of that research is 206 minus 88 percent of your age. For a 50-year-old woman, that gives 162, compared to 170 from the Fox formula.
The practical impact is significant. Using the standard male-based formula, women were more likely to receive a worse prognosis on cardiac stress tests than their actual health warranted. Many women also couldn’t reach their “target” heart rate during exercise because the target was set too high. The women-specific formula corrects for real physiological differences in exercise capacity between sexes.
Quick Reference by Age
Here’s how the three formulas compare at common ages:
- Age 30: Fox: 190 | Tanaka: 187 | Women’s: 180
- Age 40: Fox: 180 | Tanaka: 180 | Women’s: 171
- Age 50: Fox: 170 | Tanaka: 173 | Women’s: 162
- Age 60: Fox: 160 | Tanaka: 166 | Women’s: 153
- Age 70: Fox: 150 | Tanaka: 159 | Women’s: 144
Field Tests You Can Do Yourself
Formulas estimate. If you want your actual max heart rate, you need to push yourself to it. Field tests are the DIY version of a lab test, and they work well for healthy, active people who are already comfortable with high-intensity exercise.
The most common approach is a running-based test on a hill or treadmill. After a thorough 10- to 15-minute warmup, run three intervals of 2 to 3 minutes each at progressively harder effort, with equal recovery between them. On the final interval, go as hard as you can sustain for the full duration. The highest reading on your heart rate monitor during that last push is close to your true max. Some people repeat the test on a separate day to confirm the number.
A cycling version works similarly but typically produces a max heart rate 5 to 10 beats lower than running, because cycling uses less total muscle mass. If you train on a bike, use a cycling-specific test so your zones match your sport. The same principle applies to rowing, swimming, or any other activity: max heart rate is partly specific to the movement.
These tests demand genuine all-out effort, which means they’re uncomfortable by design. If you have any cardiovascular risk factors, joint issues, or haven’t exercised intensely in a long time, a supervised clinical test is a better option.
Clinical Stress Testing
The gold standard for measuring max heart rate is a graded exercise test in a clinical setting, typically done on a treadmill with continuous ECG monitoring. The most widely used version is the Bruce Protocol, which starts at a walking pace on a slight incline and increases both speed and grade every 3 minutes. By stage 3, you’re moving at 3.4 miles per hour on a 14% incline. Most people reach their max within 8 to 12 minutes.
For older adults or people with heart conditions, a modified Bruce Protocol starts with two gentler warmup stages at 1.7 mph with no incline, then 1.7 mph at a 5% grade, before progressing into the standard stages. Bicycle-based tests are also available, though treadmill testing is far more common in North America.
These tests are typically ordered for diagnostic purposes (evaluating chest pain, arrhythmias, or exercise tolerance), but your max heart rate is recorded as part of the data. If you’re already getting a stress test for any reason, ask for that number.
Getting an Accurate Reading
Your heart rate monitor matters more than you might think, especially at high intensities. Chest strap monitors that detect the heart’s electrical signal are about 99.6% accurate when positioned correctly. Wrist-based optical sensors on smartwatches work differently: they shine light through your skin to detect blood flow, which introduces a slight delay. During rapid heart rate changes like sprint intervals, a wrist sensor can lag behind your actual heart rate because blood takes time to travel from your heart to your wrist.
For everyday training, that small delay is usually fine. But if you’re doing a field test specifically to find your max, a chest strap will give you a more reliable peak number. Optical sensors can miss brief spikes that last only a few seconds, which is exactly when your true max occurs.
Factors That Shift Your Max
Max heart rate is largely genetic. Two people of the same age can have true maximums that differ by 20 or more beats per minute. Fitness level doesn’t change your max, despite a common misconception. Training lowers your resting heart rate and improves how efficiently your heart works, but the ceiling stays roughly the same throughout your adult life, declining gradually with age.
Several things can temporarily affect the number you see during a test. Dehydration, heat, altitude, caffeine, and poor sleep can all elevate heart rate, sometimes pushing readings above your typical max. Beta-blockers and some other medications cap how high your heart rate can go, making both formulas and field tests unreliable. If you take any medication that affects heart rate, your training zones should be set using a different method, such as perceived exertion or a lactate threshold test, rather than percentage of max heart rate.
Putting the Number to Use
Most people look for their max heart rate because they want to train in specific zones. The typical framework divides effort into five zones, each defined as a percentage of your max. Zone 2 (60 to 70% of max), the range that builds aerobic endurance, is the one most recreational exercisers benefit from spending the most time in. A 45-year-old with a tested max of 178 would aim for roughly 107 to 125 beats per minute for easy endurance work.
If you’ve only used a formula, start with those zones but pay attention to how they feel. If your “easy” zone feels moderate or your “hard” zone feels impossible, your estimated max is likely off. A field test or simply adjusting zones based on perceived effort will get you closer to numbers that actually match your body.