A good workout heart rate falls between 50% and 85% of your maximum heart rate, depending on your fitness goals and how hard you want to push. For most people, moderate exercise sits in the 50% to 70% range, while vigorous exercise lands between 70% and 85%. These ranges come from the American Heart Association and give you a practical target whether you’re walking briskly or doing sprint intervals.
How to Find Your Maximum Heart Rate
Your maximum heart rate is the ceiling your heart can hit during all-out effort. The simplest formula is 220 minus your age. A 40-year-old, for example, would have an estimated max of 180 beats per minute (bpm). A newer formula, 208 minus 0.7 times your age, tends to be slightly more accurate, especially as you get older. That same 40-year-old would get 180 with the newer formula too, but the gap widens at other ages.
Neither formula is perfect. A study of recreational marathon runners published in Frontiers in Physiology found that both formulas overestimated max heart rate by about 5 bpm in women, while the older 220-minus-age formula underestimated it by about 3 bpm in men. Your true max can differ from the estimate by 15 to 20 bpm in either direction. These formulas are a starting point, not a precise measurement.
Target Heart Rate by Intensity
Once you have your estimated max, multiply it by the percentage that matches your workout intensity:
- Moderate intensity (50% to 70%): Brisk walking, easy cycling, casual swimming. You can hold a full conversation. For a 35-year-old with a max of about 184 bpm, this means roughly 92 to 129 bpm.
- Vigorous intensity (70% to 85%): Running, fast cycling, competitive sports. You can speak in short phrases but not chat comfortably. That same 35-year-old would aim for about 129 to 156 bpm.
Here’s a quick reference for different ages, using the 208 minus 0.7 times age formula:
- Age 25 (max ~190): Moderate 95–133 bpm, Vigorous 133–162 bpm
- Age 35 (max ~184): Moderate 92–129 bpm, Vigorous 129–156 bpm
- Age 45 (max ~177): Moderate 89–124 bpm, Vigorous 124–150 bpm
- Age 55 (max ~170): Moderate 85–119 bpm, Vigorous 119–144 bpm
- Age 65 (max ~163): Moderate 81–114 bpm, Vigorous 114–138 bpm
What Each Zone Does for Your Body
Working out at different heart rates produces different physiological results. Lower-intensity exercise in the moderate range builds your aerobic base. Your body relies on slow, sustained fat burning for fuel, and your cardiovascular system gradually becomes more efficient. This is the zone for longer sessions where you’re building endurance or recovering from harder workouts while still staying active.
Vigorous-intensity exercise shifts your body toward burning carbohydrates for quick energy. At the higher end of this range, you’re working anaerobically, building speed, strength, and fast-twitch muscle fibers. Your heart is pumping near its capacity, which over time strengthens the heart muscle itself. Most people benefit from spending the majority of their training time in the moderate zone, with shorter bursts of vigorous effort mixed in a few times per week.
The “Fat-Burning Zone” Is Misleading
You’ve probably seen treadmills or fitness trackers label the lower heart rate zones as the “fat-burning zone.” There’s a grain of truth here: at lower intensities, a higher percentage of your calories come from fat rather than carbohydrates. But the total number of calories burned is much lower than during vigorous exercise. A 30-minute jog at 75% of your max burns more total calories, and more total fat, than 30 minutes of easy walking at 55%.
High-intensity workouts also promote fat loss through the recovery process afterward. Your body continues burning calories at an elevated rate for hours after a hard session. For overall fat loss, what matters most is total energy balance across the day and week, not staying in a specific heart rate window during any single workout.
A More Personalized Calculation
The standard percentage-of-max approach ignores one important variable: your resting heart rate. Someone with a resting heart rate of 55 bpm is more fit than someone resting at 80 bpm, and their training zones should reflect that. The Karvonen method accounts for this by using your heart rate reserve, which is simply your max heart rate minus your resting heart rate.
To use it, take your heart rate reserve, multiply it by your target percentage (say 60% for moderate work), then add your resting heart rate back. For a 40-year-old with a max of 180 and a resting rate of 60: the reserve is 120. Sixty percent of 120 is 72, plus the resting rate of 60, gives a target of 132 bpm. This method is more accurate because the fitter you are, the larger your heart rate reserve, and the harder you need to work to reach a meaningful training stimulus.
You can find your resting heart rate by checking your pulse first thing in the morning before getting out of bed, over several consecutive days, and averaging the results.
When Heart Rate Targets Don’t Apply
If you take beta-blockers or other heart rate-lowering medications, standard heart rate zones won’t work for you. These medications cap how high your heart rate can climb, so you may never reach your calculated target even during hard effort. In that case, the “talk test” and perceived exertion scales are more reliable. Most workouts should feel somewhat hard, meaning they take real effort but you can keep going. If you can’t speak at all, you’re likely pushing too hard.
An exercise stress test, done on a treadmill or stationary bike under medical supervision, can establish a personalized target heart rate if standard formulas don’t fit your situation.
Signs You’re Pushing Too Hard
Occasionally exceeding 85% of your max during a sprint or a tough hill is fine if you’re healthy. But consistently overtraining brings real risks. Warning signs include a resting heart rate that’s unusually fast (over 100 bpm) or unusually slow, persistent fatigue even after rest days, unexplained mood changes like irritability or anxiety, poor sleep, frequent minor illnesses like colds, and a sudden drop in performance despite continued training.
During a workout, sharp chest pain, dizziness, or an inability to catch your breath at an intensity that normally feels manageable are signals to stop. These aren’t signs of a good workout. They’re signs something is off.