How Calories Burned Are Estimated: METs, Units and Net Energy
An exercise calorie number is the end of a model. To interpret it, identify the activity assumption, units, duration and energy definition. The same inputs can appear to disagree when two tools report different quantities.
Follow the formula used by this site
The calculator uses the Compendium’s oxygen-based conversion:
Gross kcal = MET × 3.5 × weight in kg ÷ 200 × minutes.
Enter kilograms and minutes, not pounds or hours. The site labels the result “cal” in the everyday food-Calorie sense: the number represents kilocalories, or kcal. A displayed Calorie is not one small scientific calorie.
The selected MET is a category assumption. Standard METs make calculations comparable; they do not measure the individual’s actual expenditure.
Reproduce one calculation
For a 70-kg example using 6 MET over 30 minutes:
- 6 × 3.5 × 70 ÷ 200 = 7.35 kcal per minute.
- 7.35 × 30 = 220.5 kcal.
- Rounding the final total gives about 221 kcal.
The Calories Burned Calculator uses 6 MET for its gym-workout preset, so these inputs reproduce that case. Keep full precision while calculating and round the final result rather than every intermediate step.
Separate gross from energy above rest
Gross energy includes the energy that would be used at rest during those same minutes. Using the model’s 1-MET resting baseline gives 36.75 kcal for this person over 30 minutes. Subtracting that from 220.5 gives 183.75 kcal above that assumed resting baseline, about 184 after rounding.
This net estimate is not automatically the increment over someone’s usual day. The activity might replace walking, housework or another activity rather than resting. The relevant comparison depends on what was already included in the baseline.
Explain differences before calling them errors
A simplified MET × kilograms × hours convention gives 210 kcal for the same numerical inputs, compared with 220.5 in the site’s oxygen-based formula. State the convention rather than mixing its intermediate numbers with the other formula.
Other differences can arise from intensity selection, elapsed versus active minutes, gross versus net reporting and an individual’s physiology. More decimal places cannot repair an activity assumption that does not fit the session. To estimate a mixed workout, describe its changing effort and rest explicitly; the site’s current tool still uses one selected category across the entered time.
Frequently asked questions
Is 221 kcal an exact measurement?
No. It is the rounded result of the stated inputs and assumptions. The arithmetic can be correct while the chosen MET differs from the person’s true energy cost.
Why might a watch show fewer active Calories?
It may subtract a resting component or use a different activity model. Check the device’s metric definition before comparing it with gross session energy.
Sources and method
- Compendium of Physical Activities: Unit conversions — The oxygen-based MET-to-kcal conversion used by the site.
- Compendium of Physical Activities: Corrected METs — Standard MET values do not measure an individual’s exact energy expenditure.
Worked examples on this page are constructed to explain the method. They are not measurements of a person, food product or exercise session.
Related tools and guides
- Calories Burned Calculator — reproduce the 6-MET example
- Combine exercise estimates with TDEE — check what the full daily model already contains