Your target heart rate during exercise generally falls between 50% and 85% of your maximum heart rate, depending on how hard you’re working. For most people, maximum heart rate is roughly 220 minus your age. That means a 40-year-old has an estimated max of 180 beats per minute (bpm) and should aim for somewhere between 90 and 153 bpm during a workout.
But that range is wide for a reason. A warm-up walk and an all-out sprint place very different demands on your heart, and both count as exercise. The right target depends on your fitness goals, your age, and the type of workout you’re doing.
How to Estimate Your Maximum Heart Rate
The most common formula is simple: subtract your age from 220. A 30-year-old gets a max of 190 bpm, a 50-year-old gets 170, and so on. This method has been the standard for decades, though it can be off by 10 to 12 beats per minute in either direction. An alternative formula (multiply your age by 0.7, then subtract from 207) was developed to improve accuracy, but in practice, both formulas produce similar results for most exercisers.
If you want a more personalized number, a heart rate reserve calculation accounts for your resting heart rate too. Subtract your resting heart rate from your max heart rate to get your reserve. Then multiply that reserve by your target percentage and add your resting heart rate back in. Someone with a max of 180 and a resting rate of 65 has a reserve of 115. To hit 70% intensity, that’s (115 × 0.70) + 65 = 146 bpm. This method is more tailored because it factors in your baseline fitness level, since fitter people tend to have lower resting heart rates.
Target Heart Rates by Age
The American Heart Association provides these general target zones at 50% to 85% of maximum heart rate:
- Age 20: 100 to 170 bpm
- Age 30: 95 to 162 bpm
- Age 40: 90 to 153 bpm
- Age 50: 85 to 145 bpm
- Age 60: 80 to 136 bpm
- Age 70: 75 to 128 bpm
If you’re new to exercise or returning after a long break, staying closer to the lower end of your range (50% to 60%) is a reasonable starting point. Regular exercisers typically work in the 60% to 85% range depending on the session.
The Five Heart Rate Zones Explained
Heart rate zones break intensity into five tiers, each with a different purpose. Knowing which zone you’re in helps you match your effort to your goal instead of just going hard every session.
Zone 1 (50% to 60% of max) is your warm-up, cool-down, and recovery pace. You can hold a full conversation without effort. This zone promotes blood flow and helps your body recover between harder workouts.
Zone 2 (60% to 70% of max) is the foundation of endurance training. You’re working, but comfortably. Long runs, easy bike rides, and brisk walks typically fall here. This is the zone that builds your aerobic base over time and carries a low injury risk, making it the sweet spot for longer sessions.
Zone 3 (70% to 80% of max) feels moderately hard. Conversation becomes choppy. This zone builds both strength and endurance and is where many group fitness classes and steady-state cardio workouts land.
Zone 4 (80% to 90% of max) is a hard effort, the kind you can sustain for only a few minutes at a time. You’re approaching your limit, and talking more than a few words is difficult. Interval training and tempo runs push you into this zone to improve speed and cardiovascular power.
Zone 5 (90% to 100% of max) is an all-out sprint. You’re at peak capacity, and you can only maintain it for short bursts, typically 30 seconds to a couple of minutes. This zone strengthens fast-twitch muscle fibers and forces your heart to work at its absolute ceiling. Most people only spend a small fraction of their total training time here.
Which Zone Is Best for Your Goals
If your primary goal is general health, the American Heart Association’s guidance centers on moderate-intensity activity, which corresponds to roughly 50% to 70% of your max heart rate (Zones 1 through 2). This is the intensity level associated with reduced risk of heart disease and improved cardiovascular fitness over time. A brisk walk, a casual swim, or an easy cycling session all qualify.
For weight loss, a mix of moderate and vigorous intensities works better than sticking to one zone exclusively. Longer Zone 2 sessions burn fat efficiently because you can sustain them, while shorter bursts in Zones 4 and 5 elevate your metabolism for hours after the workout ends.
For athletic performance, you need variety across all five zones. Most coaches recommend spending the majority of training time (around 80%) in Zones 1 and 2, with the remaining 20% in high-intensity Zones 4 and 5. Zone 3, despite feeling productive, can leave you too tired to recover but not intense enough to trigger the adaptations that come from true high-intensity work.
When Heart Rate Numbers Don’t Apply
Beta-blockers and certain other blood pressure medications slow the heart rate, which means your heart rate during exercise won’t climb the way it normally would. You might never reach your calculated target zone no matter how hard you push. If you take these medications, heart rate zones become unreliable as a guide.
A practical alternative is perceived exertion, essentially rating how hard the workout feels on a scale from very light to maximum effort. One useful rule of thumb: most workouts should feel “somewhat hard,” meaning they take real effort but you can keep going. If you can’t talk at all while exercising, you’re likely pushing too hard. If you can sing, you’re not pushing hard enough.
Caffeine, dehydration, heat, stress, and poor sleep can also inflate your heart rate independently of effort. A heart rate of 160 on a hot, humid day after poor sleep doesn’t mean the same thing as 160 on a cool morning when you’re well rested. Learning to combine heart rate data with how your body feels gives you a more complete picture than either metric alone.
How Accurate Is Your Monitor
Chest strap monitors sit closest to the heart and use electrical signals similar to a medical EKG. They remain the most reliable option, particularly during high-intensity or fast-changing efforts. Wrist-based optical sensors (the kind built into smartwatches) use light to detect blood flow and work well at rest or during steady-state exercise, but their accuracy drops during activities involving a lot of wrist movement or rapid heart rate changes. One study found that wrist monitors read an average of about 20 bpm lower than chest straps during stationary cycling, a meaningful gap if you’re trying to stay in a specific zone.
For casual exercisers aiming to stay in a general range, a wrist monitor is perfectly fine. If you’re doing structured interval training and need precise zone data, a chest strap will give you more reliable numbers. Either way, treat your heart rate reading as a guide rather than gospel. A few beats per minute in either direction doesn’t change the effectiveness of your workout.
How to Check Without a Monitor
Place two fingers (index and middle) on the inside of your wrist, just below the base of your thumb. Count the beats for 15 seconds and multiply by four. That gives you a reasonable estimate of your current heart rate. The neck (carotid artery) works too, though pressing too hard there can actually slow your pulse and give you a falsely low reading.
For a quicker check, the talk test is surprisingly effective. If you can hold a conversation comfortably, you’re in a moderate zone. If you can only get out a few words between breaths, you’re in vigorous territory. If you can’t speak at all, you’re near your max. Research consistently shows a strong correlation between perceived exertion and actual heart rate, so trusting your body’s signals is a legitimate strategy, not a shortcut.