Your target heart rate is a range of beats per minute you should aim for during exercise, calculated as a percentage of your maximum heart rate. For moderate exercise, that range is 50% to 70% of your max; for vigorous exercise, it’s 70% to 85%. The math is straightforward once you know which formula to use and how to check your pulse.
Estimate Your Maximum Heart Rate
The classic formula is simple: subtract your age from 220. A 45-year-old would get a max heart rate of 175 beats per minute (bpm). This has been the standard since 1971, and it works as a rough starting point. But it has real limitations. It was originally based on studies of men, none older than 65, some of whom were on heart medications or had cardiovascular disease. Research from the Norwegian University of Science and Technology found it can underestimate max heart rate by up to 40 bpm in older adults, and inaccuracies start showing up as early as age 30 to 40.
A more refined formula, developed by researcher Hirofumi Tanaka, adjusts for these errors: 208 minus 0.7 times your age. For that same 45-year-old, this gives a max of about 177 bpm. The difference is small at younger ages but grows larger over time. At age 65, the classic formula predicts 155 bpm while the Tanaka formula predicts 162 bpm, a gap that meaningfully changes your target zones.
For women specifically, research published in the American Heart Association’s journal Circulation found that both of these formulas tend to overestimate max heart rate. A study of over 5,000 healthy women produced a more accurate formula: 206 minus 0.88 times your age. A 45-year-old woman would get roughly 166 bpm rather than the 175 the classic formula suggests. That nine-beat difference matters. The researchers noted that using male-based formulas for women leads to unrealistic heart rate targets during exercise stress tests, which may partly explain why those tests are less accurate in women.
Calculate Your Target Zone
Once you have your estimated max heart rate, your target zone is a percentage of that number. The American Heart Association defines two main zones:
- Moderate intensity: 50% to 70% of max heart rate. This is a brisk walk, easy cycling, or casual swimming.
- Vigorous intensity: 70% to 85% of max heart rate. This is running, fast cycling, or competitive sports.
For a 40-year-old using the classic formula (max of 180 bpm), moderate intensity falls between 90 and 126 bpm, and vigorous intensity between 126 and 153 bpm. If you’re new to exercise, aim for the lower end of the moderate zone and build up over time. Most healthy adults can eventually exercise comfortably at up to 85% of their max.
Use the Karvonen Method for Better Accuracy
The basic percentage method treats everyone with the same max heart rate identically, but a person with a resting heart rate of 55 bpm is in very different cardiovascular shape than someone resting at 85 bpm. The Karvonen method accounts for this by factoring in your resting heart rate. It uses something called heart rate reserve: the difference between your max and your resting heart rate.
Here’s how it works. First, find your resting heart rate by checking your pulse first thing in the morning before getting out of bed (more on how to do this below). Then subtract your resting heart rate from your max heart rate. That’s your heart rate reserve. Multiply the reserve by your target percentage, then add your resting heart rate back.
For example, a 40-year-old with a resting heart rate of 65 bpm and an estimated max of 180 bpm has a heart rate reserve of 115. To find the low end of a moderate zone (60% intensity): 115 × 0.60 = 69, plus the resting rate of 65, gives a target of 134 bpm. For the high end (80% intensity): 115 × 0.80 = 92, plus 65, gives 157 bpm. This method is commonly used in cardiac rehabilitation programs, where patients typically aim for 60% to 80% of heart rate reserve plus their resting heart rate.
The Karvonen method produces higher target numbers than the simple percentage method because it accounts for the “dead zone” between zero and your resting heart rate, where your heart is just maintaining basic body functions, not doing exercise work.
How to Check Your Pulse
You have two convenient spots to feel your pulse. The wrist (radial pulse) is the most common: turn your palm face up and place the tips of your index and middle fingers in the soft groove between the wrist bone and the tendon on the thumb side. Press lightly until you feel the beats.
The neck (carotid pulse) gives a stronger signal that’s easier to find during exercise. Place your fingertips in the groove next to your windpipe on one side of your neck. Press gently. Never press on both sides at once, as this can make you dizzy or cause you to faint. Also avoid pressing too hard, which can temporarily block blood flow.
For the most accurate reading, count the beats for a full 60 seconds. If you’re checking mid-workout, counting for 15 seconds and multiplying by four is a practical shortcut. To measure your resting heart rate, sit quietly for a few minutes before taking the count. Most healthy adults have a resting rate between 55 and 85 bpm. Well-trained athletes often land in the 40s.
When Standard Formulas Don’t Apply
Certain medications change the equation entirely. Beta blockers, prescribed for high blood pressure, irregular heart rhythms, and after heart attacks, work by slowing your heartbeat. If you take one, the standard formulas will overestimate your actual max heart rate and give you target zones you may not be able to reach, or that would represent dangerously high effort relative to your medicated heart rate. A brief exercise stress test can establish your true max so you can set accurate targets.
Fitness level also matters in ways formulas can’t capture. Two 50-year-olds can have the same estimated max heart rate but wildly different fitness levels. One might hit 85% of max on a light jog while the other needs a full sprint. This is why the Karvonen method, which incorporates resting heart rate as a rough proxy for fitness, tends to produce more personalized results. As your fitness improves and your resting heart rate drops, your target zone shifts upward automatically.
Caffeine, dehydration, stress, heat, and altitude all temporarily raise your heart rate during exercise without reflecting a change in actual effort. If you notice your heart rate seems unusually high for how hard you feel you’re working, these external factors are likely the reason. On those days, perceived effort is a better guide than the number on your watch.
Quick Reference by Age
These target zones use the classic 220-minus-age formula for simplicity. If you’re a woman or over 40, consider using the more specific formulas above for better accuracy.
- Age 25: Max 195 bpm. Moderate zone: 98 to 137. Vigorous zone: 137 to 166.
- Age 35: Max 185 bpm. Moderate zone: 93 to 130. Vigorous zone: 130 to 157.
- Age 45: Max 175 bpm. Moderate zone: 88 to 123. Vigorous zone: 123 to 149.
- Age 55: Max 165 bpm. Moderate zone: 83 to 116. Vigorous zone: 116 to 140.
- Age 65: Max 155 bpm. Moderate zone: 78 to 109. Vigorous zone: 109 to 132.