Every activity has a measured energy cost, published as a MET value. This turns that value, your weight and the time you spent into calories — and separates the calories the activity actually added from the ones your body would have spent lying still.
Key terms
- MET — metabolic equivalent of task. The Compendium of Physical Activities defines it as “the ratio of the work metabolic rate to the resting metabolic rate”, where one MET is 1 kcal per kilogram per hour, equivalent to taking in 3.5 ml of oxygen per kilogram per minute.
- Gross calories — the whole metabolic cost of the time spent. It is a multiple of your resting rate, so it includes the resting rate.
- Net calories — what the activity added on top of resting. Gross minus one hour of 1 MET for each hour spent.
- Compendium code — the five-digit identifier for each row. Every value on this page carries one, so any figure can be traced to the entry it came from.
How it works
Because one MET is defined as one kilocalorie per kilogram per hour, the arithmetic falls straight out of the definition:
Energy cost of an activity
kcal = MET × body weight in kg × hours
MET is the published value for that activity, taken from the 2024 Adult Compendium of Physical Activities. Imperial weights convert with the exact international pound, 1 lb = 0.45359237 kg.
Lying still is 1 MET, so an activity rated at 5 METs costs five times your resting rate — not five times more than it.
Why the headline number overstates the exercise
This is the part almost every calculator leaves out. A MET value is a multiple of resting metabolism, so the calories it produces include the calories you would have burned anyway. Subtracting them changes the answer by a lot, and it changes it most for the gentlest activities.
An hour of Hatha yoga at 2.3 METs is 161 kcal for a 70 kg reader. Only 91 of those were added by the yoga; the other 70 were an hour of being alive. The gross figure overstates the activity by more than three quarters. At the other end, an hour of running at 12 METs is 840 kcal gross and 770 net — the same 70 kcal of resting metabolism, now a rounding error. Both figures are shown here for exactly that reason.
What a MET value is not
It is not a measurement of you. The Compendium publishes values measured on groups of adults, and the standard it is anchored to — 3.5 ml of oxygen per kilogram per minute at rest — is a convention rather than your resting rate. Fitness, technique, terrain, heat and simple efficiency all move the real number. Treat the answer as an estimate with genuine spread around it, not a count.
It also runs one way. Knowing an hour of brisk walking cost 336 kcal tells you nothing about what you should eat, and food is far denser than exercise: that hour is roughly one large muffin. Activity is worth doing for reasons that have nothing to do with the number on this page.
How to use this calculator
- Pick the activity that most honestly matches what you did, including the effort level — the gap between “light” and “vigorous” is often double.
- Enter the minutes actually spent moving, not the time from leaving the house to getting back.
- Enter your weight; the answer scales directly with it, so a 100 kg reader burns 43% more than a 70 kg one doing exactly the same thing.
- Read the second figure, not just the first, if what you want to know is what the activity added.
- Use the comparison table to see what the same block of time costs elsewhere before deciding it was not worth it.
Frequently asked questions
Why is this number lower than the one my watch gives?
Most wearables report gross calories and estimate them from heart rate, which responds to caffeine, heat, stress and dehydration as well as effort. This page reports both gross and net from a published energy cost. The two methods disagree in both directions, and neither is measuring your metabolism directly.
Should I use the gross figure or the net one?
Net, if the question is what the exercise added. Gross, if you are accounting for a whole day’s expenditure and have not counted resting metabolism separately — using gross in a day that already includes your BMR counts the same calories twice.
Does being fitter mean I burn fewer calories?
For the same absolute work, usually a little, because you do it more efficiently. But fitter people tend to go faster or longer, which raises the MET value and more than makes the difference back. The published value is for the activity as described, so pick the description that matches what you actually did.
Why does weight change the answer so much?
Because the unit is calories per kilogram per hour. Moving a heavier body the same distance costs more energy, and the formula is linear in weight — twice the mass, twice the calories, for identical work.
Can I add these calories back into what I eat?
You can, but it is where most people come unstuck: the estimate has real error in it, and eating back an overestimate is the usual reason a deficit stops working. If you are tracking, use the net figure and treat it as approximate.
