A good heart rate during exercise falls between 50% and 85% of your maximum heart rate, depending on how hard you’re working. For most people, that translates to roughly 100 to 170 beats per minute, though your specific range depends on your age, fitness level, and whether you’re aiming for a moderate or vigorous workout.
How to Find Your Maximum Heart Rate
The most common formula is simple: subtract your age from 220. A 40-year-old, for example, has an estimated maximum heart rate of 180 beats per minute. Every target zone you calculate builds from this number.
This formula has limitations, though. It tends to underestimate maximum heart rate in older adults and can be off by several beats per minute depending on sex and fitness level. A more refined version, developed by researcher Hirofumi Tanaka, uses a slightly different calculation: 208 minus 0.7 times your age. For a 40-year-old, that gives a max of 180 as well, but the two formulas diverge more noticeably after age 50. A 60-year-old gets 160 from the standard formula but 166 from Tanaka’s. If you’re over 50, the Tanaka formula is generally considered more accurate.
Neither formula is perfect. They estimate population averages, not your individual ceiling. The only way to know your true maximum heart rate is through a supervised exercise stress test. But for everyday workout planning, these formulas are a solid starting point.
Target Zones for Moderate and Vigorous Exercise
The American Heart Association breaks exercise intensity into two main zones based on percentage of your maximum heart rate:
- Moderate intensity: 50% to 70% of maximum heart rate
- Vigorous intensity: 70% to 85% of maximum heart rate
For a 30-year-old with an estimated max of 190 bpm, moderate exercise means keeping your heart rate between 95 and 133 bpm. Vigorous exercise falls between 133 and 162 bpm. Brisk walking, casual cycling, and light swimming typically land in the moderate zone. Running, fast cycling, competitive sports, and high-intensity interval training push you into the vigorous zone.
Here’s what the ranges look like at different ages:
- Age 20: moderate 100–140 bpm, vigorous 140–170 bpm
- Age 30: moderate 95–133 bpm, vigorous 133–162 bpm
- Age 40: moderate 90–126 bpm, vigorous 126–153 bpm
- Age 50: moderate 85–119 bpm, vigorous 119–145 bpm
- Age 60: moderate 80–112 bpm, vigorous 112–136 bpm
- Age 70: moderate 75–105 bpm, vigorous 105–128 bpm
You don’t need to stay in the vigorous zone to get health benefits. Moderate-intensity exercise delivers significant cardiovascular improvement, especially if you’re just starting out or returning to exercise after a long break.
A More Personalized Calculation
The percentage-of-max approach treats everyone the same regardless of fitness. A person with a resting heart rate of 55 bpm and a person resting at 80 bpm will get identical target zones, even though their hearts are working very differently at the same exercise intensity.
The Karvonen method fixes this by factoring in your resting heart rate. First, you calculate your heart rate reserve: maximum heart rate minus resting heart rate. Then you multiply that reserve by the intensity percentage you want and add your resting heart rate back in. So a 40-year-old with a resting heart rate of 60 bpm and a max of 180 bpm has a reserve of 120. For 60% intensity, the target would be (120 × 0.60) + 60 = 132 bpm.
This method is especially useful if you’re quite fit or quite sedentary, because it accounts for the work your heart is already doing at rest. People in cardiac rehabilitation programs often use targets set at 60% to 80% of heart rate reserve.
When Heart Rate Monitors Get It Wrong
Wrist-based optical heart rate monitors are convenient, but their accuracy varies with the type of exercise. During steady-state activities like cycling or jogging at a constant pace, optical sensors can be accurate up to 98% of the time (within 5 bpm of a medical-grade reading). During weight training circuits, however, accuracy has been measured as low as 34.5%.
The biggest issue is lag. When you suddenly increase or decrease intensity, like during interval training, wrist sensors tend to undershoot during the hard effort and overshoot during recovery. They catch up once your heart rate stabilizes. If precise tracking during intervals matters to you, a chest-strap monitor is significantly more reliable. For steady-paced runs, walks, or bike rides, a wrist sensor works well enough for most people.
Why Your Heart Rate After Exercise Matters Too
How quickly your heart rate drops after you stop exercising is a meaningful indicator of cardiovascular fitness. A healthy recovery means your heart rate falls by at least 18 beats per minute within the first 60 seconds of rest. A smaller drop can signal that your cardiovascular system isn’t recovering efficiently.
You can track this easily: note your heart rate the moment you stop exercising, rest for one minute, then check again. Over weeks and months of consistent training, you should see that gap widen as your fitness improves.
When Heart Rate Targets Don’t Apply
Beta-blockers and certain other medications slow your heart rate both at rest and during exercise. If you take one of these medications, heart rate formulas won’t give you useful targets because your heart simply can’t reach the numbers the math predicts.
In that case, perceived effort is a better guide. During moderate-intensity exercise, you should be able to carry on a conversation with occasional pauses to catch your breath. If you’re breathing so hard that speaking becomes impossible, you’ve crossed into high intensity. This “talk test” is a surprisingly reliable way to gauge effort without any numbers at all, and it works for anyone, regardless of medications or individual heart rate quirks.
Signs You’re Pushing Too Hard
Staying below 85% of your maximum heart rate is the general guideline for safe exercise. Pushing beyond that range is something trained athletes do deliberately, but for most people it raises risk without proportional benefit. If you experience dizziness, chest tightness, sharp pain, or feel like you might faint, stop immediately. Nausea and an inability to catch your breath even after slowing down are also signals that your cardiovascular system is under more strain than it can handle. These symptoms warrant attention regardless of what number your watch displays.