Calories Burned Calculator

Calories burned during exercise depends on body weight, exercise intensity, duration, and metabolic efficiency. The most widely used measure of exercise intensity is MET (Metabolic Equivalent of Task), a standardized ratio comparing activity energy expenditure to resting metabolic rate.

MET-based calorie formula: Calories Burned = MET × Weight (kg) × Duration (hours)

Why this works: 1 MET = the energy cost of sitting quietly = 1 kcal per kg per hour. An activity with MET of 6 burns 6× the resting rate.

MET values, from the Compendium of Physical Activities

These are the exact values this calculator uses. Every one of them is an average across a lot of people, and individual variation of 15 to 20% is normal.

Effort level matters more than the activity name. “Weightlifting” is 3.5 or 6.0 depending on whether you are working or resting between sets, and swimming freestyle runs from 5.8 at an easy pace to 9.8 flat out. The dropdown names the effort level for that reason.

Gross versus net calories

The formula above gives gross calories, which includes the energy you would have burned anyway just being alive. For a 75 kg person that baseline is about 75 kcal an hour, so a one-hour session has roughly 75 kcal in it that you did not earn by exercising.

Net calories = (MET − 1) × weight in kg × hours

For most purposes the gross figure is what fitness trackers and treadmills report, so it is what this calculator leads with. If you are eating back exercise calories in a deficit, the net figure is the honest one, and the result panel gives both.

Worked example: A 75 kg person runs at 6 mph (MET = 9.8) for 45 minutes: Gross = 9.8 × 75 × 0.75 = 551 kcal Net = 8.8 × 75 × 0.75 = 495 kcal

Heart rate methods are more personal but need more from you

The Keytel equation estimates energy expenditure from average heart rate rather than from an activity name:

Calories/min = [(0.6309 × HR) + (0.1988 × weight in kg) + (0.2017 × age) − 55.0969] / 4.184

That is the male version; the female constants differ. It is a better fit when your effort does not match the activity label, which is common, but it needs a chest strap or watch reading you can trust. This calculator uses the MET method, not Keytel.

Afterburn effect (EPOC): High-intensity exercise elevates metabolism for hours afterwards, adding somewhere around 6 to 15% to the total for a genuinely hard session. The MET formula captures only the exercise period itself, so treat EPOC as a small bonus rather than a licence to eat one.