The most common way to calculate your maximum heart rate (MHR) is to subtract your age from 220. A 35-year-old, for example, would have an estimated MHR of 185 beats per minute. This formula is quick and widely used, but it’s not particularly accurate, and several better options exist depending on your goals.
The Standard Formula: 220 Minus Age
Known as the Fox formula, this is the version you’ll see on gym posters and fitness apps. The math is simple: MHR = 220 – your age. It gives you a ballpark number in seconds, which is why it became the default despite its limitations.
The problem is the margin of error. The standard deviation for this formula is plus or minus 15 beats per minute. That means if you’re 40 and the formula says your max is 180, your actual max could be anywhere from 165 to 195. For casual exercisers who just want a rough guide, that’s fine. For anyone training seriously or using heart rate zones to structure workouts, a 30-beat range is too wide to be useful.
More Accurate Formulas
Researchers have developed alternatives that narrow the error margin. The most well-known is the Tanaka formula: MHR = 208 – (0.7 × age). For a 40-year-old, this gives 180, which happens to match the Fox formula at that age. But the two diverge at younger and older ages. The Tanaka formula tends to be more accurate for people over 40, where the traditional formula increasingly overestimates max heart rate.
For women specifically, the Gulati formula offers a meaningful improvement. Developed from research published by the American Heart Association, it was built from data on a large group of women rather than the predominantly male populations used to create earlier formulas. The equation is: MHR = 206 – (0.88 × age). A 40-year-old woman would get an estimated MHR of about 171, noticeably lower than the 180 from the Fox formula. The traditional formula consistently overestimates max heart rate in women, so if you’re female and have felt like your “target zone” numbers seemed too high, this is likely why.
Quick Reference by Age
- Age 30: Fox = 190, Tanaka = 187, Gulati = 180
- Age 40: Fox = 180, Tanaka = 180, Gulati = 171
- Age 50: Fox = 170, Tanaka = 173, Gulati = 162
- Age 60: Fox = 160, Tanaka = 166, Gulati = 153
Finding Your Actual MHR With a Field Test
Formulas estimate. If you want your real number, you need to push your heart rate to its ceiling under controlled conditions. A hill repeat test is the most practical way to do this without a lab.
You’ll need a heart rate monitor (a chest strap is more reliable than a wrist sensor at high intensities) and ideally a training partner for safety. Here’s the protocol:
- Warm up for 15 minutes on flat ground at an easy pace.
- Find a hill that takes at least 2 minutes to climb at a running pace.
- First effort: Run up the hill building to a pace you could sustain for about 20 minutes. You don’t need to actually run for 20 minutes, just reach that intensity level. Jog back down to recover.
- Second effort: Run up again, this time faster. Push hard. Note the highest number on your heart rate monitor.
- Third effort (optional): If you felt like you had more in the tank, do one more repeat at full effort.
The peak reading from your hardest effort is your measured MHR. This number won’t change much from day to day, though it will gradually decline as you age. You don’t need to retest frequently. Once a year is plenty unless your fitness level changes dramatically.
One important note: this test requires going to maximal exertion. If you’re new to exercise, have a heart condition, or haven’t been cleared for intense activity, a supervised exercise stress test in a clinical setting is the safer route.
How to Use MHR: Heart Rate Zones
Your MHR by itself is just a number. It becomes useful when you multiply it by percentages to set training zones. The Cleveland Clinic breaks these into five tiers:
- Zone 1 (50% to 60% of MHR): Recovery pace. Light walking, gentle movement. Good for warm-ups and active rest days.
- Zone 2 (60% to 70% of MHR): Aerobic base. Comfortable enough to hold a conversation. This is where most endurance benefits happen and where the majority of your training time should fall.
- Zone 3 (70% to 80% of MHR): Moderate intensity. Conversation gets harder. Tempo runs and steady-state cardio live here.
- Zone 4 (80% to 90% of MHR): High intensity. You can only sustain this for minutes, not hours. Interval training territory.
- Zone 5 (90% to 100% of MHR): All-out effort. Sprints, race finishes, short bursts. Not sustainable for more than about 30 to 60 seconds.
To calculate your personal zones, multiply your MHR by each percentage. If your MHR is 185, your Zone 2 range is 111 to 130 bpm (185 × 0.60 and 185 × 0.70).
When Formulas Won’t Work
Beta-blockers and certain other heart medications slow your heart rate artificially, which means formula-based estimates and even field tests may not reflect your true cardiovascular effort. If you take a beta-blocker, you may never reach your calculated target heart rate regardless of how hard you push. According to the Mayo Clinic, there’s no reliable way to predict exactly how much a beta-blocker will reduce your max.
If you’re on these medications, two alternatives work better. The first is a supervised exercise stress test, which measures your actual heart rate response while accounting for the drug’s effect. The second is perceived exertion, where you rate how hard you feel you’re working on a scale of 6 to 20 (the Borg scale). A rating of 12 to 14 roughly corresponds to moderate-intensity exercise, giving you a way to gauge effort without relying on heart rate numbers at all.
Beyond medications, certain conditions can also skew results. Chronic fatigue, dehydration, heat, caffeine, and sleep deprivation all influence heart rate on any given day. Your MHR is a physiological ceiling, but your ability to reach it varies with circumstances. If your numbers seem off during a workout, trust how your body feels over what the monitor says.