A typical workout burns somewhere between 200 and 600 calories per hour, but the actual number depends heavily on what you’re doing, how hard you’re pushing, and how much you weigh. A 155-pound person burns about 288 calories running at a moderate 5 mph pace for 30 minutes, while that same person burns only 108 calories doing general weightlifting for the same duration. Those gaps widen further when you factor in body size and intensity.
Calorie Burn by Activity
Harvard Health Publishing has compiled calorie data across dozens of activities for 30-minute sessions. Here’s what the numbers look like for three different body weights:
- Walking (3.5 mph): 107 calories (125 lb), 133 calories (155 lb), 159 calories (185 lb)
- General weightlifting: 90 / 108 / 126 calories
- Vigorous weightlifting: 180 / 216 / 252 calories
- Swimming (general): 180 / 216 / 252 calories
- Stationary bike (moderate): 210 / 252 / 294 calories
- Elliptical trainer: 270 / 324 / 378 calories
- Running at 5 mph (12-min mile): 240 / 288 / 336 calories
- Running at 7.5 mph (8-min mile): 375 / 450 / 525 calories
- High-impact aerobics: 210 / 252 / 294 calories
- High-impact step aerobics: 300 / 360 / 420 calories
These are 30-minute figures. If your workout lasts 45 or 60 minutes, multiply accordingly. A 155-pound person on the elliptical for a full hour burns roughly 648 calories, while that same person doing a 60-minute general strength session burns closer to 216.
Why Body Weight Matters So Much
Your body is essentially hauling itself through space during exercise. The more mass you move, the more energy it takes. A 185-pound person running at 5 mph burns 336 calories in 30 minutes, which is 40% more than a 125-pound person doing the exact same run. This isn’t a small difference, and it’s the single biggest variable in calorie burn.
You can estimate your own burn using a straightforward formula from the University of Colorado: multiply 0.0175 by the activity’s MET value (a standardized intensity score), then multiply by your weight in kilograms. That gives you calories per minute. To convert pounds to kilograms, divide by 2.2. So a 170-pound person (77 kg) running at a moderate pace (MET of roughly 8) would burn about 0.0175 × 8 × 77 = 10.8 calories per minute, or about 324 calories in a 30-minute run.
How Intensity Changes the Equation
The difference between a casual and an aggressive workout is enormous. Moderate-intensity exercise puts your heart rate at 50% to 70% of your maximum. You’re breathing faster but can still carry on a conversation. Vigorous intensity pushes you to 70% to 85% of your max. You’ll sweat within minutes and can only manage a few words between breaths.
The calorie gap between these two zones is dramatic. A 155-pound person cycling at moderate intensity burns 252 calories in 30 minutes; at vigorous intensity, that jumps to well over 400. Similarly, general weightlifting at a leisurely pace burns 108 calories, but a circuit-style vigorous session doubles that to 216. Picking up the pace or reducing rest periods can meaningfully change your total burn without extending your workout.
Age, Sex, and Muscle Mass
You might assume that age and sex play a major role in calorie burn, but the research tells a more nuanced story. A study published in the American Journal of Clinical Nutrition found that after accounting for differences in body composition and physical activity, there was no significant sex difference in energy expenditure, and no steady linear decline with age. What did matter was how much lean mass versus fat mass a person carried. Middle-aged subjects (50 to 65) had a resting metabolic rate about 4.6% lower than younger adults, but this was a modest gap.
Muscle tissue burns roughly 4.5 to 7 calories per pound per day at rest. Fat tissue burns far less. So two people who weigh the same but carry different amounts of muscle will burn different amounts of calories doing the same activity, and throughout the rest of the day. This is one reason strength training has value beyond the calories burned during the session itself: adding muscle gradually raises your baseline energy expenditure.
The Afterburn Effect
Your body doesn’t stop burning extra calories the moment you finish exercising. After intense workouts, your metabolism stays elevated while your body restores oxygen levels, repairs muscle tissue, and clears metabolic byproducts. This is sometimes called the “afterburn effect.” It’s most pronounced after high-intensity interval training and heavy resistance training, where the demands on your body are greatest. The effect is real but modest for most people. After a typical moderate workout like a 30-minute jog, it adds relatively little. After an all-out HIIT session or a heavy lifting workout, it can meaningfully bump your total calorie expenditure for the day.
Temperature and Environment
Exercising outside the body’s comfort zone costs extra energy. When you work out in cold conditions, your body burns additional calories to maintain core temperature. Interestingly, cold exposure also tends to increase appetite afterward, with research showing higher levels of hunger-stimulating hormones and lower levels of appetite-suppressing hormones after cold exercise sessions. This means the extra calories burned may be partially offset by eating more later.
Heat works a bit differently. Exercising in hot environments doesn’t dramatically increase calorie burn, but it does temporarily suppress appetite. Studies have found that people report less hunger and eat less in the hours following a hot exercise session compared to the same workout in comfortable temperatures. The net effect on energy balance may actually favor hot conditions, not because you burn more, but because you eat less afterward.
How Accurate Is Your Fitness Tracker?
If you rely on a smartwatch or fitness band for calorie estimates, treat those numbers as rough guides. A Stanford Medicine study tested seven popular wrist-worn devices and found that even the most accurate one was off by an average of 27%. The least accurate missed by 93%. The devices did well measuring heart rate, but translating heart rate into calories burned introduces layers of estimation error. Your tracker’s number might be useful for comparing one workout to another on the same device, but the absolute calorie figure is likely off by a meaningful margin.
For a more reliable personal estimate, the MET formula (0.0175 × MET value × your weight in kilograms × minutes) gives you a solid ballpark. MET values for hundreds of activities are published in the Adult Compendium of Physical Activities, freely available online. Combining this formula with honest self-assessment of your intensity level will get you closer to the truth than most wearable devices.