Calorie burn during exercise isn't a flat number per activity — it depends heavily on your body weight, since moving more mass takes more energy, combined with how intense the specific activity is, which exercise science measures using a standardized unit called MET (Metabolic Equivalent of Task).
A MET of 1 represents your resting energy expenditure. A MET of 6, for example, means an activity burns roughly 6 times more energy than sitting still. This standardized scale lets calorie-burn calculations work consistently across completely different types of activity — walking, running, cycling, swimming — using the same underlying formula.
How Calories Burned Are Calculated
Calories Burned = (MET × Weight in kg × Duration in hours)
Common MET values: walking (slow) ≈ 3.5, jogging ≈ 6, cycling ≈ 7.5, swimming ≈ 8, HIIT ≈ 8.5, running (fast) ≈ 9.8.
A Worked Example
For a 160 lb person (72.6 kg) doing 30 minutes (0.5 hours) of jogging (MET 6): Calories = 6 × 72.6 × 0.5 ≈ 218 calories. The same person doing 30 minutes of cycling (MET 7.5) instead burns approximately 272 calories, and 30 minutes of HIIT (MET 8.5) burns roughly 309 calories — showing how meaningfully the activity type itself changes the calorie burn, even at an identical body weight and duration.
Common Mistakes to Avoid
- Assuming calorie burn is the same for everyone regardless of body weight: heavier individuals burn more calories doing the identical activity for the identical duration, since more mass requires more energy to move.
- Overestimating calorie burn from fitness trackers: many consumer devices overestimate calorie burn by a meaningful margin — MET-based estimates from verified research tend to be more conservative and reliable.
- Using calorie burn alone to justify food choices: it's easy to overestimate exercise calorie burn and underestimate food calorie intake, a common combination that stalls weight loss progress.
- Ignoring that intensity within an activity matters too: "running" covers a wide range of paces with different MET values — a faster pace burns meaningfully more than a slower one at the same duration.
Bottom Line
Calorie burn scales with both your body weight and the activity's intensity, not a flat number per activity. Use a Calories Burned Calculator with your weight, duration, and activity type for a realistic estimate of any workout's calorie cost.