Your target heart rate is the range of heartbeats per minute you should aim for during exercise to get the most benefit without overexerting yourself. For most people, that range falls between 50% and 85% of your maximum heart rate, which translates to roughly 100 to 170 beats per minute for a 20-year-old and 80 to 136 bpm for a 60-year-old.
How to Calculate Your Maximum Heart Rate
The simplest formula is 220 minus your age. If you’re 40, your estimated maximum heart rate is 180 bpm. This is the ceiling, the fastest your heart should beat during all-out effort. Your target heart rate zones are then calculated as percentages of that number.
This formula can be off by 10 to 12 beats per minute in either direction. A more refined alternative: multiply your age by 0.7, then subtract that number from 207. For a 40-year-old, that gives 179 instead of 180, a small difference at that age but a more meaningful one for older adults. Either way, these are estimates. The only precise way to know your true maximum is through a supervised stress test.
Target Heart Rate Zones by Age
The American Heart Association publishes a widely referenced chart using the 50% to 85% range of maximum heart rate:
- Age 20: 100 to 170 bpm (max: 200)
- Age 30: 95 to 162 bpm (max: 190)
- Age 40: 90 to 153 bpm (max: 180)
- Age 50: 85 to 145 bpm (max: 170)
- Age 60: 80 to 136 bpm (max: 160)
- Age 70: 75 to 128 bpm (max: 150)
If you’re just starting an exercise routine, aim for the lower end of your range (50% to 60%) and gradually work up. Experienced exercisers can safely train in the upper zones.
Moderate vs. Vigorous Intensity
Not all exercise needs to push you to 85% of your max. Moderate-intensity exercise, like brisk walking or casual cycling, puts you at 50% to about 70% of your maximum heart rate. You can carry on a conversation, though you’ll notice your breathing is heavier than normal.
Vigorous-intensity exercise, like running, swimming laps, or high-intensity interval training, pushes you to 70% to about 85%. Talking becomes difficult, and you’ll be breathing hard. Both levels offer cardiovascular benefits. Most health guidelines recommend a mix of the two throughout your week.
The Five Training Zones
Many fitness apps and wearables break your target heart rate into five zones, each with a different purpose:
- Zone 1 (50% to 60%): Easy effort. You can hold a full conversation. This is your warm-up, cool-down, and recovery zone.
- Zone 2 (60% to 70%): Light effort. You can still talk but might pause to catch your breath. Ideal for longer cardio sessions that build endurance.
- Zone 3 (70% to 80%): Comfortably hard. Conversation drops off as breathing intensifies. Good for building both strength and endurance.
- Zone 4 (80% to 90%): Hard effort. Talking takes real work. This zone builds speed and power, and you can only sustain it for shorter intervals.
- Zone 5 (90% to 100%): Maximum effort. You’re gasping, not talking. Reserved for brief, all-out bursts that train your heart at peak capacity and build fast-twitch muscle fibers.
Most of your weekly exercise should fall in Zones 2 and 3. Zones 4 and 5 are useful for interval training but aren’t meant to be sustained for long periods.
A More Personalized Calculation
The basic formula (220 minus age) ignores your fitness level entirely. A more accurate approach, sometimes called the Karvonen method, factors in 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. A normal resting rate for most adults is 60 to 100 bpm. If you’re physically active, yours might be in the 50s. Well-trained athletes often sit in the 40s. Next, calculate your heart rate reserve: subtract your resting heart rate from your maximum heart rate. Then multiply that reserve by your desired training percentage and add your resting heart rate back.
For example, a 40-year-old with a resting heart rate of 65 bpm who wants to train at 70% intensity would calculate: maximum heart rate (180) minus resting heart rate (65) equals a reserve of 115. Multiply 115 by 0.70 to get 80.5, then add the resting heart rate back: 80.5 plus 65 equals about 146 bpm. Compare that to the simpler method (70% of 180 = 126 bpm), and you can see the Karvonen approach gives a meaningfully different, and more personalized, number.
When Standard Targets Don’t Apply
Beta-blockers and certain other blood pressure medications slow your heart rate by design. If you take one, you may never reach your standard target heart rate no matter how hard you push. Using heart rate as your guide in this situation can lead you to dangerously overexert yourself trying to hit a number your medication won’t let you reach.
Instead, use perceived exertion. The simplest version: if you can talk but not sing during exercise, 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 talk at all, ease up. Most workouts should feel like they take real effort, but you can keep going.
This perceived exertion approach is also useful if you have an irregular heart rhythm, are pregnant, or have any condition that makes standard heart rate formulas unreliable.
How Accurate Is Your Wearable?
Wrist-based heart rate monitors (the optical sensors in smartwatches) are generally reliable during activities like jogging and walking, where your wrist stays relatively stable. But accuracy drops during certain exercises. Research comparing wrist monitors to chest straps found that during stationary cycling, wrist sensors recorded heart rates roughly 20 beats per minute lower than chest-strap readings, a significant undercount that could place you in the wrong training zone entirely.
During walking and jogging, the difference between wrist and chest readings was not statistically significant. If you want the most accurate real-time data, especially for cycling or activities with a lot of wrist movement, a chest-strap monitor is the better choice. For casual fitness tracking during runs or walks, a wrist-based device works fine.
Warning Signs You’re Pushing Too Hard
Briefly exceeding your target zone during a sprint or tough hill isn’t necessarily dangerous for a healthy person. But sustained effort well above your target range can strain your cardiovascular system. Pay attention to dizziness, lightheadedness, chest pain, heart palpitations, or feeling like you might faint. Nausea and unusual shortness of breath (beyond what you’d expect from the effort) are also signals to stop and rest. These symptoms during exercise warrant immediate medical attention, not a “push through it” mentality.