Your target heart rate during exercise depends on your age and how hard you’re pushing. For moderate workouts like brisk walking or easy cycling, aim for 50% to 70% of your maximum heart rate. For vigorous exercise like running or high-intensity intervals, the target rises to 70% to 85%. Going above 85% is generally unnecessary for health benefits and harder to sustain safely.
To use those percentages, you first need to estimate your maximum heart rate. From there, the math is simple, and you can dial in a range that matches your fitness goals.
How to Estimate Your Maximum Heart Rate
The classic formula is 220 minus your age. A 40-year-old gets a max of 180 beats per minute (bpm). It’s easy to remember, but it has known blind spots: it tends to underestimate max heart rate in older adults and can be off by 10 to 12 bpm in either direction for any individual.
A slightly more accurate alternative, developed by researcher Hirofumi Tanaka, uses a different calculation: 208 minus 0.7 times your age. For that same 40-year-old, the result is 180 bpm (the two formulas happen to converge near age 40). But they diverge at the extremes. A 25-year-old gets 195 from the classic formula and 190 from Tanaka’s. A 60-year-old gets 160 versus 166. Research in physically active adults and people carrying extra weight has found Tanaka’s formula tends to land closer to actual measured values. Either formula gives you a reasonable starting point, not a precise number.
Here are quick reference estimates using the 220-minus-age formula:
- Age 25: max ~195 bpm, moderate zone 98–137, vigorous zone 137–166
- Age 35: max ~185 bpm, moderate zone 93–130, vigorous zone 130–157
- Age 45: max ~175 bpm, moderate zone 88–123, vigorous zone 123–149
- Age 55: max ~165 bpm, moderate zone 83–116, vigorous zone 116–140
- Age 65: max ~155 bpm, moderate zone 78–109, vigorous zone 109–132
A More Personalized Calculation
The percentages above treat everyone of the same age identically. A more individualized approach, called the Karvonen method, factors in your resting heart rate. Someone with a resting heart rate of 55 bpm is starting from a different baseline than someone at 75 bpm, and their target zones should reflect that.
The steps are straightforward. First, find your resting heart rate by checking your pulse first thing in the morning before getting out of bed. Count the beats for 60 seconds (or for 15 seconds and multiply by four). Then calculate your heart rate reserve: subtract your resting heart rate from your estimated maximum. Finally, multiply that reserve by the percentage you want, and add your resting heart rate back.
For example, a 40-year-old with a resting heart rate of 65 bpm has a max of about 180 and a heart rate reserve of 115. To find the lower end of moderate intensity (50%), the math is: 115 × 0.50 + 65 = 123 bpm. The upper end of vigorous (85%) is: 115 × 0.85 + 65 = 163 bpm. This method is commonly used in cardiac rehabilitation programs, where patients typically target 60% to 80% of heart rate reserve plus their resting rate.
What Each Zone Actually Does
The moderate zone (50% to 70% of max) is where most health benefits accumulate. Walking fast enough that you can talk but not sing, casual cycling, water aerobics, and light hiking all fall here. This range improves cardiovascular health, lowers blood pressure over time, and burns a meaningful number of calories without heavy strain.
The vigorous zone (70% to 85% of max) pushes your cardiovascular system harder. Running, fast cycling, swimming laps, and competitive sports typically land here. You can speak in short phrases but can’t hold a conversation. Training in this range builds endurance, increases your heart’s stroke volume (how much blood it pumps per beat), and improves your body’s ability to use oxygen efficiently.
You don’t need to pick one zone and stay there. Most effective training plans mix both. Easy days in the moderate range build your aerobic base and aid recovery, while harder sessions in the vigorous range push your fitness forward.
The “Fat Burning Zone” Is Misleading
Many treadmills and fitness trackers highlight a “fat burning zone” around 50% to 70% of max heart rate. The logic is that your body burns a higher percentage of calories from fat at lower intensities. That’s technically true. But the total number of calories burned is lower, which means the actual amount of fat lost is often similar to, or less than, what you’d lose at higher intensities.
Research has found the optimal heart rate range for fat oxidation is broadly between 60% and 80% of max, overlapping heavily with the vigorous zone. More importantly, the American Council on Exercise has noted that a person burns fat regardless of which “zone” they’re in during exercise. For weight loss, the total calories you burn matters far more than the fuel source your body happens to favor at a given intensity. If you enjoy lower-intensity exercise and do more of it, that’s a perfectly valid approach. Just don’t avoid pushing harder because you think it wastes fat-burning potential.
How Accurate Is Your Wrist Monitor?
If you’re tracking heart rate with a smartwatch or fitness band, the numbers are useful as a general guide but not gospel. A 2017 study presented at the American College of Cardiology found that wrist-worn optical sensors had an error range of plus or minus 15 to 34 bpm depending on the activity. Their agreement with medical-grade EKG readings ranged from 0.67 to 0.92 on a scale where 1.0 is a perfect match. Chest strap monitors performed far better, landing at 0.996 agreement with EKG.
Wrist sensors become less accurate as exercise intensity increases, partly because arm movement and sweat interfere with the optical reading. If precision matters to you, a chest strap paired with your watch will give much more reliable data. For most people doing general fitness training, a wrist monitor is good enough to keep you in the right neighborhood.
When Your Heart Rate Won’t Match the Charts
Several factors can shift your heart rate response in ways that make standard targets unreliable. Beta-blockers, commonly prescribed for high blood pressure, slow the heart rate and can make it impossible to reach your calculated target no matter how hard you exercise. If you take one, heart rate zones based on age alone won’t apply to you, and the perceived exertion method (gauging effort by how hard you feel you’re working on a 1-to-10 scale) becomes more practical.
Caffeine, dehydration, heat, altitude, stress, and sleep deprivation all push heart rate higher at the same effort level. A run that normally keeps you at 145 bpm might register 155 on a hot, humid day after poor sleep. That doesn’t mean you’re working harder in any productive sense. It means your heart is compensating for extra strain. On those days, paying attention to how you feel is more reliable than chasing a number.
One Metric Worth Tracking After Your Workout
How quickly your heart rate drops after you stop exercising is a useful indicator of cardiovascular fitness. This is called heart rate recovery. The benchmark: your heart rate should drop by at least 18 beats within one minute of stopping vigorous exercise. A larger drop generally signals a healthier, more efficient cardiovascular system.
To measure it, note your heart rate the moment you stop your hardest effort, then check it again after standing or walking slowly for exactly 60 seconds. If the drop is consistently below 12 bpm, that’s worth mentioning at your next physical. Over weeks and months of consistent training, you should see this number improve, which is one of the most tangible signs that your heart is getting stronger.