The quickest way to estimate your max heart rate is to subtract your age from 220. A 40-year-old gets 180 bpm. But that number can be off by 7 to 10 beats in either direction, which is enough to throw off your training zones. There are better formulas, a simple field test you can do on a hill, and ways to use your result that actually matter for fitness.
The Standard Formula and Why It’s Imprecise
The “220 minus age” formula has been around since the 1970s. It’s easy to remember, and it does give a reasonable ballpark. In a study of 230 adults who completed graded exercise tests in a lab, this formula had a mean absolute error of about 7.7 bpm compared to their actual measured max heart rate. That means for any given person, the formula’s prediction could land nearly 8 beats too high or too low on average, with some individuals seeing even larger gaps.
Interestingly, this old formula had one advantage over newer alternatives: it was the only one in the study that didn’t show proportional bias. That means it didn’t systematically get worse for people with especially high or low max heart rates. It’s imprecise for individuals, but it’s consistently imprecise rather than skewing in one direction.
A More Accurate Formula
A formula developed by researcher Hirofumi Tanaka performs slightly better overall: 208 minus (0.7 × your age). For a 40-year-old, that gives 180 bpm, the same as the old formula. But the two diverge at younger and older ages. A 25-year-old gets 195 from the classic formula but 190.5 from Tanaka’s. A 60-year-old gets 160 versus 166.
In the same lab study, the Tanaka formula consistently produced the lowest error rates, with a mean absolute error of 7.4 bpm and a root-mean-square error of 9.2 bpm. The tradeoff is that it tends to underestimate max heart rate for people whose true max is on the higher end. If you’re very fit and regularly hit high heart rates during intense exercise, this formula may lowball your number.
For women specifically, the Gulati formula offers another option: 206 minus (0.88 × age). It was derived from a large study of asymptomatic women and may better reflect the slightly different rate at which women’s max heart rate declines with age.
How to Test It Yourself
Formulas are estimates. If you want a number closer to your actual max, a field test with a heart rate monitor will get you there. You’ll need a hill that takes at least two minutes to climb and, ideally, a training partner for safety.
- Warm up for 15 minutes on flat ground, gradually building to your normal training pace.
- Run up the hill at a pace you think you could sustain for about 20 minutes. Push hard but controlled.
- Jog back down to recover, then run up the hill again, this time pushing as hard as you can for the full climb.
- Check your monitor. The highest number you hit on that second effort is a close approximation of your max heart rate.
This test works because it forces your cardiovascular system to its limit without requiring a treadmill or lab equipment. The first hill effort primes your body. The second one, done at full intensity, pushes you to the ceiling. If the number you see is significantly different from what a formula predicted, trust the test. Your body doesn’t care about equations.
One important note: if you haven’t been exercising regularly, or if you have a heart condition, high blood pressure, or chest pain with exertion, a supervised stress test at a clinic is the safer route. These use a treadmill protocol that increases speed and incline in stages while monitoring your heart rhythm continuously.
What Can Shift Your Max Heart Rate
Max heart rate is largely genetic. Two people the same age, same fitness level, can have max heart rates that differ by 20 bpm or more. Training doesn’t raise it. Getting fitter improves how efficiently your heart pumps blood at every heart rate, but it won’t push your ceiling higher. In fact, max heart rate drops by roughly 0.7 to 1 beat per year as you age, and no amount of exercise changes that trajectory.
Certain medications directly lower your max heart rate. Beta blockers, commonly prescribed for high blood pressure and heart rhythm issues, slow the heart’s response to exertion. If you take one, the American Heart Association recommends that you not rely on any age-based formula. Instead, your doctor can determine your adjusted target through a brief exercise stress test, since beta blockers affect each person differently. In the meantime, a practical alternative is the talk test: at moderate intensity, your heart beats faster and you breathe harder, but you can still hold a conversation.
Heat, dehydration, and altitude can also affect what you see on your monitor during any given workout, though they don’t change your true physiological max. A high reading on a hot day may reflect cardiovascular strain rather than a higher ceiling.
Turning Your Max 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 185 bpm max is 130 bpm, a solid moderate-intensity target. But a more personalized approach uses something called heart rate reserve.
Heart rate reserve is the gap between your max heart rate and your resting heart rate. If your max is 185 and your resting heart rate (measured first thing in the morning, lying still) is 60, your reserve is 125 beats. To find a target zone, you multiply the reserve by your desired intensity percentage, then add your resting heart rate back in. For a 60% intensity workout: 125 × 0.60 = 75, plus 60 = 135 bpm. For 80% intensity: 125 × 0.80 = 100, plus 60 = 160 bpm.
This method, sometimes called the Karvonen method, accounts for your baseline fitness. Two people with the same max heart rate but different resting heart rates will get different targets, and that’s the point. Someone with a resting heart rate of 50 has more cardiovascular headroom than someone resting at 75, even if their ceilings match. Cardiac rehab programs typically use 60% to 80% of heart rate reserve to set exercise intensity, but recreational athletes can use the same approach for everything from easy recovery runs to tempo workouts.
Which Method to Choose
If you just need a quick number to program into a fitness watch, the Tanaka formula (208 minus 0.7 times your age) is your best bet for accuracy. If you’re a woman, try the Gulati formula and see how it compares. If you’re serious about dialing in your training and you’re healthy enough for high-intensity effort, do the hill test once or twice a year. Your true max may surprise you in either direction.
Whatever number you land on, pair it with your resting heart rate to build zones using heart rate reserve. A formula that’s off by a few beats matters less when you’re using a method that adjusts for your individual physiology.