The simplest way to estimate your maximum heart rate is to subtract your age from 220. A 40-year-old gets an estimate of 180 beats per minute. But this classic formula can be off by as much as 18 to 24 beats in either direction, which is a big enough gap to throw off your entire training plan. More accurate options exist, from updated formulas to field tests you can do yourself.
The Standard Formulas and Their Limits
The “220 minus age” formula, developed by Fox in the 1970s, remains the most widely used estimate. It’s simple, but it was never meant to be precise for individuals. A more recent formula by Tanaka calculates max heart rate as 208 minus 0.7 times your age, which tends to be more accurate for older adults. For a 50-year-old, Fox predicts 170 bpm while Tanaka predicts 173 bpm. The gap widens with age: at 70, Fox gives 150 while Tanaka gives 159.
For women specifically, research published in Circulation found that male-based formulas overestimate peak heart rate. A formula developed from a large cohort of asymptomatic women uses 206 minus 0.88 times age. At age 45, this gives a woman an estimated max of roughly 166 bpm, compared to 175 from the standard Fox formula. That nine-beat difference matters when you’re setting training zones or evaluating cardiovascular fitness.
The real problem with all formulas is individual variation. A large analysis in PLOS ONE found that while the average error across formulas was relatively small (ranging from negative 3 to positive 6 bpm), the limits of agreement spanned roughly 18 to 24 beats in either direction. That means two healthy 35-year-olds could have true max heart rates of 168 and 200, yet the formula gives them both 185. If you need precision, you need a test.
The Hill Repeat Field Test
A field test is the most practical way to find your actual max heart rate without a lab visit. You’ll need a heart rate monitor (a chest strap is ideal at high intensities) and a hill that takes at least two minutes to climb. Bring a training partner for safety. Here’s the protocol:
- Warm up for 15 minutes at an easy pace on flat ground, gradually building to your normal training effort.
- First hill effort: Run up the hill for at least two minutes at a pace you could sustain for about 20 minutes. This isn’t a sprint. Jog back down.
- Second hill effort: Run up again faster, at a pace you could hold for roughly 3 kilometers. Note your peak heart rate reading. Your true max is likely about 10 beats higher than this number.
- Recovery: Jog back down and let your heart rate drop by 30 to 40 beats.
- Third hill effort: Run up at a pace you can only hold for one minute. Go as hard as you can for about half the hill. The highest number on your monitor during this effort is close to your true maximum.
- Cool down for at least 10 minutes.
This test works because the progressive efforts push your cardiovascular system to its ceiling without the shock of starting cold. The third effort, coming on top of already-accumulated fatigue, forces your heart rate to its peak. Don’t attempt this test without a solid fitness base. If you haven’t been exercising regularly, start with the formulas and work up to testing after several weeks of consistent training.
Laboratory Testing
The gold-standard measurement happens during a graded exercise test, typically on a treadmill using a protocol that increases both speed and incline every three minutes. The most common version starts at a walking pace of 1.7 mph on a 10% incline and ramps up through progressively harder stages, eventually reaching 5.0 mph at an 18% grade. Your heart is monitored continuously with electrodes, and the test continues until you physically can’t keep going.
Lab tests are more accurate than field tests because they use medical-grade ECG equipment, control the environment, and have trained staff watching your heart rhythm in real time. They also capture your heart rate recovery, which is a useful indicator of cardiovascular health on its own. A healthy heart rate should drop by 18 beats or more within the first minute after stopping maximal effort. A slower recovery can signal reduced fitness or underlying cardiac risk.
The downside is access and cost. These tests are typically ordered for medical reasons or available through sports performance labs, and they can run several hundred dollars out of pocket.
Why Your Max Heart Rate Is Unique to You
Maximum heart rate is largely determined by genetics and age. No amount of training will raise it. Research from the American Heart Association shows that max heart rate declines by about 4% to 6% per decade, with a slightly steeper drop in older age groups. This decline happens at roughly the same rate regardless of fitness level. A sedentary person and a lifelong runner of the same age will have similar max heart rates, even though their overall cardiovascular fitness is very different.
Altitude also plays a role. At elevation, your heart rate runs higher during submaximal exercise but your achievable maximum actually drops compared to sea level. Research published in Circulation found that this reduction is driven by changes in the nervous system’s control of the heart, not by the heart muscle itself. If you train at altitude, your max heart rate numbers from sea level won’t apply.
When Medications Change the Number
Beta-blockers, commonly prescribed for high blood pressure, anxiety, and certain heart conditions, significantly lower your maximum heart rate. In one study, people taking beta-blockers reached an average max of about 138 bpm compared to 154 bpm in those not on the medication. That’s a 16-beat difference that makes standard formulas and percentage-based training zones unreliable.
If you take beta-blockers, age-based formulas will overestimate your max. Researchers have proposed adjusted formulas for this population, but the most practical approach is to use perceived exertion instead: a scale of 1 to 10 where your hardest sustainable effort is about a 7 or 8. This lets you train by feel rather than chasing a heart rate number your medication won’t let you reach.
Choosing the Right Heart Rate Monitor
At maximum effort, your choice of monitor matters. Chest straps use electrical signals similar to a medical ECG and remain accurate even during intense, erratic movement. Optical wrist sensors, which use light to detect blood flow, can struggle when your arms are moving fast or when sweat disrupts the sensor’s contact with your skin.
Studies comparing the two have found significant discrepancies during certain activities, with wrist monitors reading higher or lower than chest straps by a meaningful margin during some exercises. For steady-state activities like cycling, the gap narrows. But if you’re doing a max heart rate field test with hill sprints or high-intensity intervals, a chest strap will give you a more trustworthy peak reading.
Putting Your Max Heart Rate to Use
Once you have your number, the main application is setting heart rate training zones. Most systems divide effort into five zones based on percentages of your max. Zone 2, the range most associated with building aerobic fitness and burning fat, typically falls between 60% and 70% of max. Threshold training sits around 80% to 90%, and anything above 90% is reserved for short, high-intensity intervals.
The accuracy of these zones depends entirely on the accuracy of your max heart rate input. Using a formula-based estimate that’s 15 beats too high means your “easy” zone is actually moderate, and your threshold zone is actually near-max. This is the most common reason people feel like they can’t sustain their prescribed training paces. If your zones feel consistently wrong, a field test to pin down your real maximum is worth the effort.