Your target heart rate during exercise is 50% to 85% of your maximum heart rate, depending on how hard you want to work. Maximum heart rate is roughly 220 minus your age. So a 40-year-old has a max of about 180 beats per minute (bpm) and a target range of 90 to 153 bpm during workouts. That range spans everything from an easy walk to a hard run, and where you aim within it depends on your fitness level and goals.
How to Calculate Your Max Heart Rate
The simplest formula is 220 minus your age. It’s the standard the American Heart Association uses, and it gives you a quick ballpark. A 30-year-old gets a max of 190 bpm; a 55-year-old gets 165 bpm.
That formula can be off by 10 to 12 beats per minute in either direction. A more accurate version, developed from a large meta-analysis of heart rate studies, is 208 minus (0.7 × your age). For a 50-year-old, the classic formula gives 170 bpm while the updated one gives 173 bpm. The gap widens at older ages: a 70-year-old gets 150 with the classic formula but 159 with the updated one. Either works as a starting point, but the updated formula tends to be more reliable for people over 40.
Moderate vs. Vigorous Intensity
The American Heart Association breaks exercise into two main intensity bands based on your max heart rate:
- Moderate intensity: 50% to 70% of max. This is a brisk walk, easy cycling, or casual swimming. You can hold a conversation comfortably.
- Vigorous intensity: 70% to 85% of max. This is jogging, fast cycling, or an intense group fitness class. Talking becomes difficult.
If you’re new to exercise, start at the lower end (around 50%) and build up over weeks or months. Jumping straight to 85% without a fitness base increases injury risk and makes workouts feel miserable.
Target Heart Rates by Age
Here’s what the ranges look like at different ages, using the 220-minus-age formula:
- Age 25: Max 195 bpm. Target zone: 98 to 166 bpm.
- Age 35: Max 185 bpm. Target zone: 93 to 157 bpm.
- Age 45: Max 175 bpm. Target zone: 88 to 149 bpm.
- Age 55: Max 165 bpm. Target zone: 83 to 140 bpm.
- Age 65: Max 155 bpm. Target zone: 78 to 132 bpm.
A More Personalized Calculation
The basic percentage method ignores one important variable: your resting heart rate. Someone who’s very fit might have a resting rate of 55 bpm, while someone who’s sedentary might sit at 85 bpm. Those two people will experience the same target number very differently.
The heart rate reserve method accounts for this. Here’s how it works:
- Find your max heart rate (220 minus your age).
- Subtract your resting heart rate. The result is your heart rate reserve.
- Multiply that reserve by the intensity percentage you want (say 60%).
- Add your resting heart rate back to the result.
Example: a 45-year-old with a resting heart rate of 68 bpm aiming for 60% intensity. Max is 175. Reserve is 175 minus 68, which equals 107. Multiply 107 by 0.60 to get 64. Add the resting rate back: 64 plus 68 equals 132 bpm. That’s a more tailored target than simply taking 60% of 175 (which would be 105 bpm, a number that barely counts as exercise for most people).
The Five Heart Rate Zones
Fitness trackers and gym equipment often divide effort into five zones. Each one feels different and uses fuel differently.
Zone 1 (50% to 60% of max) is a warm-up or recovery pace. You can chat easily. Your body runs almost entirely on stored fat for fuel. Think of a leisurely walk or gentle stretching.
Zone 2 (60% to 70%) is where most endurance training happens. You can talk but might pause to catch your breath. Still primarily burning fat. This is the sweet spot for longer cardio sessions, like a 45-minute jog or a steady bike ride.
Zone 3 (70% to 80%) feels comfortably hard. Conversation drops to short phrases. Your body starts pulling from carbohydrates and protein alongside fat. This zone builds both strength and aerobic capacity.
Zone 4 (80% to 90%) is high intensity. Talking takes real effort. Your body shifts to burning mostly carbohydrates. Workouts here improve speed and power but are taxing enough that one or two sessions per week is plenty.
Zone 5 (90% to 100%) is an all-out sprint. You’re gasping, not talking. This strengthens your heart by forcing it to work at peak capacity and builds fast-twitch muscle fibers. These efforts last seconds to a few minutes, not sustained sessions.
If weight loss is a primary goal, spending most of your workout time in zones 1 through 3 is more effective than pushing to zones 4 and 5. Lower-intensity exercise draws more heavily on stored fat, while high-intensity work burns through your carbohydrate reserves instead.
What Affects Your Resting Heart Rate
Your resting heart rate is the baseline your targets are built on, and it fluctuates more than most people realize. A normal resting rate falls between 60 and 100 bpm, but well-trained athletes can sit in the 40s or 50s because their hearts pump more blood per beat.
Stress and anxiety raise it. So does caffeine, which can keep your rate elevated for an hour or more. High cholesterol restricts blood flow through arteries, which forces the heart to beat faster to compensate. Certain medications, including some antidepressants and blood pressure drugs, push the number up or down. Even a poor night of sleep can add several beats per minute to your baseline the next morning.
To get an accurate resting rate, measure it first thing in the morning before getting out of bed. Place two fingers on the inside of your wrist, just below the base of your thumb, or on the side of your neck. Count the beats for 60 seconds. A quicker method is counting for 15 seconds and multiplying by four. Do this on a few different mornings and average the results.
Beta-Blockers and Heart Rate Targets
If you take beta-blockers for blood pressure or a heart condition, the standard formulas won’t work for you. These medications deliberately lower both your resting and peak heart rates, which means your actual maximum will be significantly below what any age-based formula predicts.
Research on cardiac rehab patients found that people on beta-blockers need adjusted targets. Where someone not on beta-blockers might aim for 85% of their max, a person taking these medications gets similar training benefit at around 80%, and the heart rate reserve method works better with a 60% target rather than 70%. The safest approach is to have your target set during a supervised exercise test, where your actual peak heart rate on medication can be measured directly.
How to Check Your Heart Rate During Exercise
A chest strap heart rate monitor gives the most accurate real-time readings. Wrist-based fitness trackers are convenient but can lag behind during intense intervals or read inaccurately if the band is too loose.
For a manual check mid-workout, stop briefly and press two fingers against your neck or wrist. Count beats for 15 seconds and multiply by four. This isn’t perfect since your heart rate starts dropping the moment you stop moving, but it’s close enough to tell whether you’re in the right zone. Over time, most people develop a sense of what each zone feels like and rely less on counting. The talk test is surprisingly reliable: if you can sing, you’re in zone 1 or 2; if you can speak in sentences, you’re in zone 3; if you can only manage a few words, you’re in zone 4 or above.