Your target heart rate is a range of beats per minute that tells you you’re exercising hard enough to improve fitness but not so hard that you’re overdoing it. For moderate exercise, that range is 50 to 70 percent of your maximum heart rate. For vigorous exercise, it’s 70 to 85 percent. Finding these numbers takes about 30 seconds of math once you know two things: your age and, for a more precise calculation, your resting heart rate.
The Basic Formula
The most widely used starting point is simple: subtract your age from 220. That gives you an estimated maximum heart rate, the theoretical ceiling for how fast your heart can beat during all-out effort. A 40-year-old, for example, has an estimated max of 180 beats per minute.
From there, you multiply by the intensity percentage you want. For that same 40-year-old aiming for moderate exercise at 50 to 70 percent:
- Low end: 180 × 0.50 = 90 bpm
- High end: 180 × 0.70 = 126 bpm
For vigorous exercise at 70 to 85 percent:
- Low end: 180 × 0.70 = 126 bpm
- High end: 180 × 0.85 = 153 bpm
This formula is a rough estimate. It can be off by 10 to 12 beats per minute in either direction, which is why researchers have proposed an alternative: multiply your age by 0.7, then subtract from 207. For that 40-year-old, that gives a max of 179 instead of 180, a small difference at that age but a more meaningful one for older adults.
A More Personalized Calculation
The basic formula treats everyone the same age identically. The Karvonen method improves on this by factoring in your resting heart rate, which reflects your individual fitness level. Someone with a resting rate of 55 bpm is in a very different place than someone at 85 bpm, even if they’re the same age.
Here’s how it works, step by step:
- Step 1: Find your maximum heart rate (220 minus your age).
- Step 2: Subtract your resting heart rate. This number is your heart rate reserve.
- Step 3: Multiply your heart rate reserve by your desired intensity (for example, 0.60 for 60 percent).
- Step 4: Add your resting heart rate back to the result.
For a 40-year-old with a resting heart rate of 70 bpm, targeting 60 percent intensity: max heart rate is 180, heart rate reserve is 110 (180 minus 70), 60 percent of 110 is 66, and adding the resting rate back gives a target of 136 bpm. Compare that to the basic formula’s answer of 108 bpm at 60 percent. The Karvonen method typically produces a higher, more realistic target because it accounts for your baseline. People in cardiac rehab programs commonly aim for 60 to 80 percent of heart rate reserve plus resting heart rate.
How to Measure Your Resting Heart Rate
A normal resting heart rate for most adults falls between 60 and 100 bpm. If you’re very fit, yours could be in the 40s or 50s. Caffeine, alcohol, stress, sleep quality, weight, and certain medications can all shift the number, so measure it under calm, consistent conditions.
The best time is first thing in the morning, before you get out of bed. Place the tips of your index and middle fingers on the inside of your wrist, between the bone and the tendon on the thumb side. Press lightly until you feel each beat, then count for a full 60 seconds. Pressing too hard can actually block blood flow and give you a false reading. If you prefer, count for 15 seconds and multiply by four.
You can also check the pulse at your neck. Find the groove next to your windpipe on one side and press gently with two fingertips. Never press both sides of your neck at the same time, as this can make you dizzy or faint. Do this for a few mornings in a row and average the results for the most reliable baseline.
Checking Your Heart Rate During Exercise
A fitness watch or chest strap heart rate monitor is the easiest way to track your pulse mid-workout. But if you don’t have one, you can stop briefly and take a manual pulse at your wrist or neck. Count for 15 seconds and multiply by four. The number drops quickly once you stop moving, so start counting immediately.
If you’re in the right zone, you should be able to carry on a conversation during moderate exercise, though not effortlessly. During vigorous exercise, talking becomes difficult, and you can manage only a few words at a time before needing a breath.
Gauging Intensity Without a Monitor
You don’t necessarily need to count beats at all. The Borg Rating of Perceived Exertion scale lets you estimate intensity based on how your body feels. It runs from 6 (no exertion, like sitting still) to 20 (absolute maximum effort). A rating between 12 and 14 reflects moderate to somewhat hard intensity, which lines up well with the 50 to 70 percent heart rate zone. A rating of 15 to 17 corresponds to vigorous effort.
The numbers on the scale were originally designed to roughly correspond to heart rate when you add a zero. A perceived exertion of 13, for instance, loosely maps to about 130 bpm. It’s not precise, but it gives you a useful internal compass once you learn to pay attention to your breathing rate, muscle fatigue, and how much effort each minute feels like it takes. For most workouts, you want to feel like the exercise takes real work but you can keep going.
When Standard Formulas Don’t Apply
Beta-blockers and certain other heart medications slow your heart rate by design. If you take one, you may never reach your calculated target heart rate no matter how hard you push. The formula still gives you a number, but that number becomes meaningless as a guide because the medication has changed the relationship between effort and heart rate.
In this situation, perceived exertion becomes your primary tool. The talk test works well here: if you can’t speak during exercise, you’re likely working too hard regardless of what the monitor says. Your doctor can also order an exercise stress test, which measures how hard your heart actually pumps while you walk on a treadmill or ride a stationary bike, giving you a personalized target that accounts for the medication’s effects.
Putting It All Together
If you want a quick answer and you’re generally healthy, the basic formula (220 minus age, then multiply by 0.50 to 0.85) gives you a workable range within a couple of minutes. If you want something more tailored to your fitness level, take your resting heart rate over a few mornings and use the Karvonen method. Either way, treat the result as a guide, not a hard boundary. Your body’s signals, how you breathe, how your muscles feel, whether you can talk, are just as valuable as the number on a screen.