Your target heart rate is a range, typically 50% to 85% of your maximum heart rate, that tells you whether you’re working hard enough during exercise to get real cardiovascular benefits. Figuring it out takes about 30 seconds of math once you know two numbers: your age and, for a more personalized result, your resting heart rate.
Estimate Your Maximum Heart Rate
The simplest formula is 220 minus your age. If you’re 40, your estimated max heart rate is 180 beats per minute. This formula has been used for decades, but it’s a rough estimate. A more accurate version, developed from a large meta-analysis published in the Journal of the American College of Cardiology, is 208 minus 0.7 times your age. For a 40-year-old, that gives 180 as well, but the two formulas diverge more at older ages. A 65-year-old gets 155 with the simple formula but 162 with the updated one.
Neither formula is precise for every individual. The standard deviation around these estimates is about 10 beats per minute, meaning your true max could be 10 or even 20 beats higher or lower than what the math predicts. Both formulas also tend to overestimate max heart rate in women. Still, they give you a useful starting point. If you want a truly accurate number, a graded exercise test supervised by a professional is the gold standard.
The Simple Percentage Method
Once you have your estimated max heart rate, the American Heart Association recommends these two intensity bands:
- Moderate intensity: 50% to 70% of your max heart rate
- Vigorous intensity: 70% to 85% of your max heart rate
For a 40-year-old with an estimated max of 180, moderate intensity means keeping your heart rate between 90 and 126 beats per minute. Vigorous intensity means 126 to 153. If you’re just getting into regular exercise, aiming for the moderate range is a solid place to start. As your fitness improves, you can push into the vigorous zone for shorter periods.
The Heart Rate Reserve Method
The simple percentage method ignores one important variable: how fit you already are. Two people who are both 40 might have very different resting heart rates. An athlete could sit at 48 beats per minute while a sedentary person could be at 85. The heart rate reserve method, also called the Karvonen method, accounts for this difference and gives you a more personalized target.
Here’s how it works, step by step:
First, find your resting heart rate. Measure it first thing in the morning before you get out of bed, counting your pulse for a full 60 seconds. Do this a few days in a row and use the average. A normal resting heart rate for most adults is 60 to 100 beats per minute, though athletes often land in the 40s or 50s.
Second, calculate your heart rate reserve. Subtract your resting heart rate from your estimated max heart rate. For a 40-year-old with a max of 180 and a resting rate of 70, the heart rate reserve is 110.
Third, apply your desired intensity percentage. Multiply your heart rate reserve by the percentage, then add your resting heart rate back. If you want to exercise at 60% intensity: 110 × 0.60 = 66, plus 70 = 136 beats per minute. For 80% intensity: 110 × 0.80 = 88, plus 70 = 158 beats per minute. Your target zone at 60% to 80% intensity would be 136 to 158.
Notice how different this is from the simple percentage method. Sixty percent of 180 is only 108, but 60% of heart rate reserve plus resting rate gives 136. The Karvonen method produces a higher and more realistic target because it recognizes that your heart doesn’t start from zero when you begin exercising.
Heart Rate Training Zones
Many fitness trackers and gym programs break intensity into five zones based on percentage of max heart rate. You don’t need to memorize all five, but two are especially useful for most people.
Zone 2, which falls at roughly 60% to 70% of your max, is the endurance zone. This is a pace where you can carry on a conversation but still feel like you’re working. It’s the sweet spot for longer cardio sessions, building aerobic fitness, and limiting injury risk. Most of your weekly exercise time should probably live here.
Zone 5, at 90% to 100% of your max, is peak effort. You can only sustain this for short bursts. Training here strengthens your heart by forcing it to work at peak capacity and builds the fast-twitch muscle fibers used in sprinting and explosive movements. Interval training typically involves brief dips into this zone followed by recovery.
How to Check Your Heart Rate During Exercise
The easiest approach is a chest strap or wrist-based heart rate monitor. Chest straps tend to be more accurate during vigorous activity because wrist sensors can lose the signal when you’re sweating heavily or gripping equipment tightly.
If you don’t have a device, you can check your pulse manually. Place two fingers on the inside of your wrist just below the base of your thumb, or on the side of your neck beside your windpipe. Count the beats for 10 seconds and multiply by six. Do this within a few seconds of pausing your exercise, because your heart rate drops quickly once you stop moving.
When the Formulas Don’t Apply
Beta-blockers and certain other blood pressure medications lower your heart rate artificially, which means the standard formulas will overestimate what you can actually reach. If you take these medications, heart rate targets based on age alone won’t be reliable. A better alternative is the perceived exertion scale, where you rate how hard you feel you’re working on a scale from 1 to 10. Moderate exercise feels like a 4 to 6, and vigorous exercise feels like a 7 or 8.
Perceived exertion is also a useful backup for anyone who finds the math cumbersome. If you can talk but not sing during your workout, you’re in the moderate zone. If you can only get out a few words at a time, you’re in the vigorous zone. These simple checks line up well with heart rate targets for most people and require no formulas at all.
A Quick Example to Tie It Together
Say you’re 50 years old with a resting heart rate of 68. Using the updated formula, your estimated max is 208 minus 35, which is 173. Your heart rate reserve is 173 minus 68, giving you 105. If you want to exercise at a moderate 60% to 70% of heart rate reserve, your target range is:
- Lower end: 105 × 0.60 + 68 = 131 bpm
- Upper end: 105 × 0.70 + 68 = 142 bpm
That 131 to 142 range is your personalized moderate-intensity target. Staying within it during a brisk walk, bike ride, or swim means you’re getting meaningful cardiovascular benefit without overexerting. As your fitness improves over weeks and months, your resting heart rate will likely drop, which changes the math. Recalculating every few months keeps your targets accurate.