The quickest way to estimate your maximum heart rate is to subtract your age from 220. A 40-year-old gets 180 beats per minute (bpm). But that simple formula can be off by 10 to 15 bpm in either direction, which is a big enough gap to throw off your training zones or mislead you about your fitness. There are more accurate formulas, field tests you can do on your own, and clinical tests that give you a precise number.
The Classic Formula and Its Limits
The “220 minus age” formula dates back to the 1970s and remains the most widely cited method. It’s a rough average, not a personal measurement. Age alone accounts for somewhere between 35% and 80% of the variation in max heart rate across individuals, with standard deviations of 10 to 15 bpm in large studies. That means two healthy 35-year-olds could have true max heart rates of 170 and 200, yet the formula gives both of them 185.
The formula also wasn’t designed with women in mind. Several updated versions try to close that gap:
- Fox (the classic): 220 minus your age
- Tanaka: 208 minus 0.7 times your age
- Gellish: 207 minus 0.7 times your age
- Nes: 211 minus 0.64 times your age
- Fairbairn (sex-specific): Men get 208 minus 0.8 times age; women get 201 minus 0.63 times age
For a 45-year-old man, these formulas produce estimates ranging from 172 to 182 bpm. The Tanaka and Gellish formulas tend to be more accurate for older adults than the Fox formula, which progressively overestimates max heart rate with age. If you just need a ballpark number to set up a fitness watch or loosely guide your workouts, any of these will do. If you want real precision, you need to test yourself.
How to Test It Yourself
A field test pushes you to a genuine all-out effort so you can read your actual peak heart rate from a monitor. You’ll need a heart rate monitor (a chest strap is ideal) and, ideally, a training partner nearby for safety.
The Hill Test
This is one of the most reliable self-tests for runners and cyclists. Start with a 15-minute warm-up on flat ground, gradually building to your normal training pace. Then find a hill that takes at least two minutes to climb. Run up the hill at the hardest pace you think you could sustain for about 20 minutes. Return to the bottom and repeat the climb, this time pushing even harder in the final 60 seconds. Check your heart rate monitor at the very top. The highest number you see is close to your max.
The Treadmill Ramp
If you don’t have a good hill nearby, you can replicate the test on a treadmill. After a thorough warm-up, increase the speed or incline every one to two minutes. Keep going until you physically cannot maintain the pace. Your peak reading in those last seconds is your max heart rate. Having someone stand next to the treadmill is a smart precaution when you’re running to complete exhaustion.
A few practical tips make these tests more reliable. Do the test when you’re well rested, not at the end of a hard training week. Avoid caffeine for at least a few hours beforehand, since it can nudge your heart rate up artificially. And repeat the test on a different day to confirm. If you get 188 one day and 191 the next, your max is likely around 191. The true max is the highest number you can reproduce.
Clinical Stress Testing
A graded exercise test in a medical setting is the gold standard. You walk on a treadmill while sensors track your heart’s electrical activity and your blood pressure. The test starts slow, under 2 mph, and every three minutes the speed and incline ramp up. In the most common version, called the Bruce protocol, there are seven stages. By the final stage you’d be walking at 5.5 mph up a 20% grade. Clinicians monitor you throughout and typically aim to get your heart working to at least 85% of its predicted maximum.
Most people don’t need a clinical test just to find their max heart rate. These tests are primarily used to screen for heart problems or evaluate cardiac risk. But if you have a heart condition, take medications that affect heart rate, or haven’t exercised in years and want to start training at high intensities, a supervised test gives you the safest and most accurate number.
Why Your Monitor Matters
When you’re sprinting up a hill gasping for air, you need your heart rate monitor to keep up. Chest straps use electrical signals, the same basic technology as a hospital ECG, and hit about 99.6% accuracy when worn snugly. Wrist-based optical sensors work well at rest and moderate effort, but during vigorous exercise they can lag behind or misread. Fast arm movements cause the sensor to bounce, and reduced blood flow to your extremities during hard effort makes the optical signal weaker.
If you’re doing a max heart rate test, a chest strap is worth borrowing or buying. The peak number is the whole point of the test, and a wrist sensor might catch up a few seconds too late or miss the true spike entirely.
Medications That Change the Number
Beta-blockers, commonly prescribed for high blood pressure and certain heart conditions, directly lower your maximum heart rate. Studies on patients taking beta-blockers found their actual max heart rate followed a completely different pattern: roughly 183 minus 0.76 times age, compared to about 210 minus 0.91 times age for people not on beta-blockers. For a 50-year-old, that’s a difference of roughly 20 bpm.
If you take beta-blockers and plug your age into a standard formula, you’ll get a number you can never actually reach. Your training zones will be set too high, and you’ll wonder why you can’t hit them. Some other medications, including certain antidepressants and calcium channel blockers, can also blunt your heart rate response. In these cases, using a perceived exertion scale alongside heart rate is a more practical way to gauge intensity.
Turning Max Heart Rate Into Training Zones
Knowing your max heart rate is only useful if you apply it. The simplest approach is to calculate percentages of your max: 60% to 70% for easy efforts, 70% to 80% for moderate aerobic training, and 80% to 90% for threshold and interval work.
A more personalized method factors in your resting heart rate. Called the Karvonen method, it works like this: subtract your resting heart rate from your max heart rate to get your heart rate reserve. Then multiply that reserve by the percentage you want, and add your resting heart rate back. For example, if your max is 190 and your resting heart rate is 60, your reserve is 130. For a 70% effort, that’s (130 × 0.70) + 60 = 151 bpm. This approach accounts for your baseline fitness, because two people with the same max heart rate but different resting rates are at very different levels of cardiovascular conditioning.
Your resting heart rate is easy to measure: check your pulse first thing in the morning before getting out of bed, and average several days. Most fitness watches track this automatically.
What Affects Your Max Heart Rate
Max heart rate is largely genetic. Two people of the same age and fitness level can have max rates that differ by 20 bpm or more, and that’s completely normal. Training doesn’t raise your max heart rate. It may even drop slightly over a lifetime of endurance training. What training does change is your efficiency at every percentage of max, your resting heart rate, and how quickly you recover.
Altitude, dehydration, heat, and sleep deprivation can all shift your heart rate on a given day. If you test yourself at sea level and then train at elevation, your heart rate at the same effort will be higher, but your true max won’t change meaningfully. Age is the biggest predictor of decline: max heart rate drops roughly 0.7 bpm per year on average, which is why most formulas use age as the main variable.
If your formula-predicted max feels wrong during workouts, it probably is. A field test takes 30 minutes and gives you a number you can actually trust.