Your heart rate during exercise should generally fall between 50% and 85% of your maximum heart rate, depending on how intense you want your workout to be. For most adults, that translates to roughly 95 to 170 beats per minute, with your specific range determined mainly by your age and fitness level.
How to Find Your Maximum Heart Rate
Every target exercise heart rate starts with one number: your estimated maximum heart rate. The simplest way to calculate it is to subtract your age from 220. A 40-year-old, for example, has an estimated max of 180 beats per minute. This formula (known as the Fox formula) has been used since 1971 and remains the most widely referenced starting point.
A newer calculation multiplies your age by 0.7, then subtracts that from 208. For a 40-year-old, that gives a max of 180 as well, but the two formulas diverge at other ages. The newer version tends to be slightly more accurate for men, while both formulas overestimate max heart rate in women by about 5 beats per minute. Neither is perfect. Both can be off by 10 to 12 beats per minute in either direction, so treat your calculated max as an estimate, not a hard ceiling.
Target Heart Rate by Age
The American Heart Association defines two main exercise intensity zones. Moderate intensity sits at 50% to 70% of your max heart rate. Vigorous intensity runs from 70% to 85%. Here’s what that looks like in actual beats per minute, based on Cleveland Clinic guidelines:
- Age 20: 120 to 170 bpm
- Age 30: 114 to 162 bpm
- Age 40: 108 to 153 bpm
- Age 50: 102 to 145 bpm
- Age 60: 96 to 136 bpm
- Age 70: 90 to 123 bpm
If you’re just starting an exercise routine or returning after a long break, aim for the lower end of your range. As your fitness improves over weeks and months, you can gradually push toward the higher end.
A More Personalized Calculation
The ranges above treat everyone of the same age identically, but two 40-year-olds can have very different baseline fitness levels. A more personalized approach factors in your resting heart rate, which reflects your current cardiovascular conditioning. This method is called the heart rate reserve formula.
Here’s how it works. First, measure your resting heart rate by checking your pulse first thing in the morning before getting out of bed. Then subtract that resting number from your estimated maximum. The result is your heart rate reserve. To find a target, multiply that reserve by the percentage of intensity you want (say, 0.60 for 60%), then add your resting heart rate back in.
For example, a 45-year-old with a resting heart rate of 65 has an estimated max of 175. Their reserve is 110 (175 minus 65). At 60% intensity, their target would be 131 bpm (110 × 0.60 + 65). Compare that to the simpler method, which would put 60% of max at just 105 bpm. The difference matters because the reserve method accounts for fitness you’ve already built.
Why Fitness Level Changes Everything
Trained athletes typically have resting heart rates around 60 to 62 bpm, while sedentary adults average closer to 78 bpm. That gap reflects a stronger, more efficient heart that pumps more blood per beat and doesn’t need to work as hard at rest or during exercise. In studies comparing athletes to sedentary individuals during the same workouts, athletes maintained proportionately lower heart rates at the same effort level, reaching around 113 bpm where sedentary participants climbed to about 134 bpm.
This is why a fit person and an unfit person shouldn’t chase the same heart rate number. If you’ve been training consistently for years, your heart rate during a moderate jog might be 120 bpm. For someone just starting out, the same pace could push them to 155. Both might be working at the same relative intensity for their bodies. The percentage-based zones adjust for this automatically, especially when you use the heart rate reserve method.
Factors That Shift Your Heart Rate
Your heart rate during the same workout can vary by 10 to 20 beats from one day to the next, and that’s normal. Several factors push it higher without any change in effort.
Heat is one of the biggest. When temperatures climb above 40°C (104°F), your heart has to work significantly harder because it’s pumping blood to your skin for cooling while also fueling your muscles. Dehydration amplifies this effect. Even mild fluid loss increases cardiovascular strain, forcing your heart to beat faster to maintain the same output. On hot days or during long workouts, your heart rate will drift upward even if you maintain a steady pace.
Caffeine, poor sleep, stress, and illness can all elevate your exercise heart rate as well. If your heart rate seems unusually high for a familiar workout, it’s worth considering whether one of these factors is at play rather than assuming you’ve lost fitness overnight.
When Heart Rate Monitoring Won’t Work
Certain medications make heart rate an unreliable guide to exercise intensity. Beta-blockers, commonly prescribed for high blood pressure and heart conditions, directly suppress your heart rate. If you take one, you may never reach your calculated target heart rate no matter how hard you push. Using standard heart rate zones could lead you to overexert yourself trying to hit a number your medication won’t allow.
In this situation, perceived exertion is a better tool. The Borg Rating of Perceived Exertion scale runs from 6 (no effort at all) to 20 (absolute maximum). A rating of 12 to 14, described as “somewhat hard,” corresponds roughly to moderate-intensity exercise. At this level, you’re breathing harder than normal but can still hold a conversation. If you can’t talk while exercising, you’re likely pushing too hard. Most workouts should feel like they take real effort but remain sustainable.
The talk test works even without a numbered scale. During moderate exercise, you can talk but not sing. During vigorous exercise, you can only get out a few words before needing a breath. These cues are free, require no equipment, and work regardless of medications or heart rate variability.
Signs You’re Pushing Too Hard
Your heart rate rising during exercise is entirely normal. That’s your cardiovascular system doing its job. But certain symptoms during a workout signal that something is off. Dizziness, lightheadedness, chest pain, heart palpitations that feel irregular or pounding, and unusual shortness of breath that doesn’t match your effort level all warrant stopping immediately.
After you stop exercising, your heart rate should begin dropping fairly quickly. A heart rate that stays elevated well above 100 bpm for more than several minutes after you’ve stopped and are resting comfortably is worth paying attention to, particularly if it’s accompanied by any of the symptoms above. A normal post-exercise recovery sees your heart rate drop noticeably within the first minute or two of rest.
How to Check Your Heart Rate Mid-Workout
The easiest method is a wrist-based fitness tracker or chest strap heart rate monitor, which gives you a continuous reading. If you don’t have one, you can check manually. Press two fingers (not your thumb) against the inside of your wrist or the side of your neck. Count the beats for 15 seconds and multiply by four.
Checking mid-workout gives you a snapshot, but don’t obsess over hitting an exact number. Your target zone is a range for a reason. If you’re within 5 to 10 beats of your intended zone and the effort feels right, you’re getting the benefit. Over time, you’ll develop an intuitive sense of what moderate and vigorous intensity feel like in your body, and you won’t need to check as often.