During moderate exercise, your heart rate should be between 50% and 70% of your maximum heart rate. During vigorous exercise, aim for 70% to 85%. For a 40-year-old, that translates roughly to 90–126 beats per minute for a brisk walk and 126–153 bpm for a hard run. Your specific numbers depend on your age, resting heart rate, fitness level, and whether you take certain medications.
How to Find Your Maximum Heart Rate
Every target heart rate zone starts with one number: your estimated maximum heart rate. The simplest formula, and the one most people have heard, is 220 minus your age. A 35-year-old gets a max of 185 bpm; a 60-year-old gets 160 bpm. It’s easy to remember and, despite being decades old, performs reasonably well across a wide range of people.
A slightly more accurate version, developed by researcher Hirofumi Tanaka, uses the formula 208 minus (0.7 × age). For a 45-year-old, that gives a max of about 177 bpm instead of 175. A large study comparing seven prediction formulas found that Tanaka’s equation (along with two similar ones) produced the lowest average error. The classic 220-minus-age formula was the most consistent across different heart rate ranges, though, making it a perfectly fine starting point.
The key thing to understand is that all of these formulas carry a margin of error of roughly 18 to 24 bpm in either direction. Two 50-year-olds can have true maximums that differ by 40 beats. So treat any calculated number as an estimate, not a hard boundary.
A Note for Women
The standard formulas were originally developed using mostly male subjects. Research published in the American Heart Association’s journal Circulation found that a more accurate formula for women is 206 minus (0.88 × age). For a 50-year-old woman, that gives a max of 162 bpm rather than the 170 that 220-minus-age would predict. The traditional formula tends to overestimate maximum heart rate in women, which can make target zones misleadingly high.
Target Heart Rate Zones by Age
Using the American Heart Association’s recommended percentages and the 220-minus-age formula, here are approximate target ranges:
- Age 25: Max 195 bpm. Moderate: 98–137. Vigorous: 137–166.
- Age 30: Max 190 bpm. Moderate: 95–133. Vigorous: 133–162.
- Age 35: Max 185 bpm. Moderate: 93–130. Vigorous: 130–157.
- Age 40: Max 180 bpm. Moderate: 90–126. Vigorous: 126–153.
- Age 45: Max 175 bpm. Moderate: 88–123. Vigorous: 123–149.
- Age 50: Max 170 bpm. Moderate: 85–119. Vigorous: 119–145.
- Age 55: Max 165 bpm. Moderate: 83–116. Vigorous: 116–140.
- Age 60: Max 160 bpm. Moderate: 80–112. Vigorous: 112–136.
- Age 65: Max 155 bpm. Moderate: 78–109. Vigorous: 109–132.
Moderate intensity is what you’d feel during a brisk walk or easy bike ride. Vigorous intensity is what you’d feel during jogging, swimming laps, or cycling uphill.
A More Personalized Calculation
The percentage-of-max method treats everyone the same age as identical, but a fit person with a resting heart rate of 55 and a sedentary person resting at 80 are starting from very different baselines. The heart rate reserve method (sometimes called the Karvonen method) accounts for this by folding in your resting heart rate.
The formula: (maximum heart rate minus resting heart rate) × desired intensity percentage, then add resting heart rate back. Say you’re 40 with a resting heart rate of 65. Your heart rate reserve is 180 minus 65, which equals 115. For moderate exercise at 60% intensity: 115 × 0.60 = 69, plus 65 = 134 bpm. For vigorous exercise at 80%: 115 × 0.80 = 92, plus 65 = 157 bpm.
This method gives a more individualized target and is widely used in cardiac rehabilitation programs, where patients typically aim for 60% to 80% of heart rate reserve plus their resting heart rate.
The Anaerobic Threshold
As you increase intensity, there’s a tipping point where your body can no longer fuel your muscles with oxygen alone and starts relying more heavily on anaerobic energy production. This is the anaerobic threshold, and it typically occurs at about 60% of your maximum oxygen uptake in average adults. Below this point, your body clears lactic acid as fast as it produces it. Above it, lactate builds up, your breathing becomes noticeably harder, and you can only sustain the effort for a limited time.
You don’t need lab testing to sense this threshold. It’s roughly where you shift from being able to hold a conversation to only managing a few words at a time. Trained endurance athletes can push this threshold higher, which is why a competitive runner can hold a pace that would leave a beginner gasping within minutes.
When Heart Rate Targets Don’t Apply
Beta blockers and certain other blood pressure medications suppress your heart rate, both at rest and during exercise. If you take a beta blocker, your heart rate may stay 10 or more beats per minute lower than it would otherwise. One approach is to subtract the same amount the medication lowered your resting rate from your target zone. But beta blockers can also blunt the normal rise in heart rate during exercise in unpredictable ways, making heart rate an unreliable gauge of effort.
In these cases, perceived exertion is a better tool. The Borg scale, a widely used rating system, runs from 6 (no exertion at all) to 20 (maximum effort). Moderate exercise falls around 12 to 13, described as “somewhat hard.” Vigorous exercise is around 15 to 17, described as “hard” to “very hard.” The scale correlates well with heart rate in people who aren’t on heart-rate-altering medications, but its real value is that it works even when heart rate doesn’t tell the full story. If you can talk but not sing, you’re in the moderate zone. If you can only say a few words before needing a breath, you’re in the vigorous zone.
How Accurate Is Your Wrist Monitor?
Optical sensors on smartwatches and fitness bands measure heart rate by shining light through your skin and detecting changes in blood flow. During running, these sensors are within 10 bpm of a chest strap reference about 95% of the time, with an average error of around 2 bpm. That’s good enough for training in a target zone. During less rhythmic activities like gym circuits or strength training, accuracy drops slightly, with coverage falling to about 92%.
Chest straps remain the gold standard for precision. They detect electrical signals from the heart directly and have almost no lag. If you’re doing interval training where you need to hit precise heart rate targets within a few beats, a chest strap is worth using. For general zone training during a jog or bike ride, a wrist sensor does the job.
Heart Rate Recovery as a Fitness Marker
How quickly your heart rate drops after you stop exercising tells you something about your cardiovascular fitness. A healthy benchmark is a drop of at least 18 beats per minute within the first minute of rest. A faster recovery generally indicates better fitness and a well-functioning autonomic nervous system. If your heart rate barely budges in that first minute, it may be worth mentioning to your doctor, as sluggish recovery has been linked to higher cardiovascular risk in research studies.
Tracking your recovery over weeks and months can be more useful than tracking your exercise heart rate alone. As your fitness improves, you’ll often notice your heart rate recovers faster even before your resting heart rate changes.