How to Calculate Calories Burned During Exercise
The most widely used method for estimating exercise calorie expenditure uses Metabolic Equivalent of Task (MET) values. A MET of 1.0 is the energy used at rest (sitting quietly). Running at 10 km/h has a MET of ~10, meaning it burns 10× more calories per minute than rest.
The Formula
Calories burned = MET × weight(kg) × duration(hours)MET Values for Common Activities
- Walking (5 km/h): MET 3.5
- Cycling (16–19 km/h): MET 8.0
- Running (8 km/h): MET 8.3
- Running (12 km/h): MET 11.5
- Swimming (moderate): MET 7.0
- Weight training (moderate): MET 5.0
- HIIT: MET 8.0–14.0
- Yoga: MET 3.0
- Rowing (vigorous): MET 12.0
Example: 75 kg person, 45-minute run at 10 km/h (MET 10)
Calories = 10 × 75 × 0.75 = 563 kcalAfterburn Effect (EPOC)
High-intensity exercise creates Excess Post-exercise Oxygen Consumption (EPOC), burning an additional 6–15% of calories for up to 24 hours after the session. This is why HIIT burns more total calories than the session itself suggests.
Find your calorie targets: Free Calorie Calculator
MET Values for Common Activities
The Metabolic Equivalent of Task (MET) quantifies activity intensity. 1 MET = resting metabolic rate ≈ 1 kcal/kg/hour. Calories burned = MET × body weight (kg) × duration (hours). Common MET values: sitting (1.3), walking at 3 mph (3.5), jogging at 5 mph (8.3), running at 7 mph (11.0), swimming laps (8.0), cycling at 12–14 mph (8.0), HIIT (8.0–12.0), strength training (3.5–5.0). A 70 kg person running for 30 minutes at 7 mph burns approximately 70 × 11.0 × 0.5 = 385 kcal.
Factors That Affect Calorie Burn
- Body weight: Heavier individuals burn more calories performing the same activity because more mass must be moved. A 90 kg runner burns roughly 30% more than a 70 kg runner at the same pace.
- Fitness level: Trained athletes are more metabolically efficient, burning slightly fewer calories than beginners for the same workload.
- Age: Resting metabolic rate declines approximately 2–3% per decade after age 30, reducing total daily calorie burn.
- Sex: Men typically have higher LBM and therefore higher resting metabolic rates than women of the same body weight, resulting in higher calorie burn during identical activities.
- Temperature: Cold environments increase calorie burn as the body uses energy to maintain core temperature.
Frequently Asked Questions
How accurate are calorie burn calculators?
MET-based calculators are estimates with margins of error of 10–20% for most people. Individual metabolic variation, exercise efficiency, terrain, and environmental factors all affect actual calorie burn. For serious training, a heart rate monitor paired with power measurement (cycling) or VO2 max testing provides more accurate estimates.
Does muscle burn more calories than fat at rest?
Yes, but not as dramatically as often claimed. One kilogram of muscle burns approximately 13 kcal/day at rest; one kilogram of fat burns approximately 4.5 kcal/day. Adding 5 kg of muscle increases resting metabolic rate by roughly 65 kcal/day — meaningful over years but modest in the short term.
Should I eat back the calories I burn during exercise?
This depends on your goal. For weight maintenance, eating back exercise calories is appropriate. For weight loss, many dietitians recommend eating back only 50–75% of estimated exercise calories, as both food logging and calorie burn calculators tend to overestimate. For athletic performance, adequate fuelling is essential — under-eating relative to training load impairs recovery and increases injury risk.