Calories Burned Calculator

How to use the calories burned calculator

Pick an activity, enter your weight, and enter the minutes you spent moving. The calculator multiplies the activity MET value by 3.5 millilitres of oxygen per kilogram per minute, converts that oxygen into energy at 5 kilocalories per litre, and multiplies by the time. The result appears with the Compendium activity code it came from.

The fields open on a representative case: 30 minutes of brisk walking at 70 kg, which is Compendium code 17200 at 4.8 MET. That produces 176 kcal gross, 37 kcal of which is the resting share, leaving 140 kcal as the extra energy the walk itself required.

Two of those three inputs behave in a way worth knowing before you read the answer. Weight and time both scale the result in a straight line: at the same MET, doubling either doubles the calories, and the same activity costs a 90 kg body half again what it costs a 60 kg body.

The activity choice is the one that does not behave simply, because you are not choosing an effort level, you are choosing a published measurement of a named activity. Picking the nearest-sounding label rather than the matching one is the most common way to get a wrong number out of a correct formula.

The gross and net distinction is the part most calculators skip. If you sit on the sofa for 30 minutes you still spend energy, roughly 37 kcal for a 70 kg body, and a MET calculation counts that same energy inside its total because the MET scale is anchored at rest rather than at zero.

So a 30 minute walk did not add 176 kcal to your day. It added about 140, because the other 37 were happening regardless. The gap grows as the activity gets gentler: at 2.3 MET, more than two fifths of the reported total is resting energy that was never optional.

Three reasons this number runs high

The MET method is useful and cheap and it has three known biases, all of them pushing the same way. None is a reason to ignore the result. All three are reasons to read it as an estimate with a wide band around it.

The MET value was measured on other people

Every MET value in the Compendium is an average across a group of volunteers performing a named activity. The 2024 Adult Compendium lists 1,114 activities, 912 of them from measured data and 202 estimated, and it is built for adults aged 19 to 59. Your own cost for the same activity sits somewhere around that average, not on it.

The resting rate in the formula is not yours

The 3.5 millilitres of oxygen per kilogram per minute that defines 1 MET traces back to the resting oxygen uptake of a single 70 kg, 40-year-old man. Byrne and colleagues measured 642 women and 127 men aged 18 to 74 and found a mean resting uptake of 2.6 millilitres per kilogram per minute.

That gap is about a third, and it runs in one direction: a formula anchored at 3.5 hands back a larger number than one anchored at a measured resting rate would. The effect is strongest for the people furthest from that original 70 kg, 40-year-old man.

It does not subtract the time you were alive anyway

The third bias is arithmetic rather than physiology, and it is the easiest to correct. A MET total counts the energy you would have spent doing nothing at all during those minutes. This tool reports that share separately so you can take it off, and most calculators do not.

Reading the Compendium properly

The Compendium of Physical Activities is a published catalogue, first released in 1993 and updated in 2000, 2011 and 2024. Every entry carries a five-digit code: the first two digits are the major heading and the last three identify the specific activity within it.

Code 17200 breaks down as major heading 17, Walking, and activity 200, which is walking at 3.5 to 3.9 mph on a level firm surface at a brisk pace. That precision is the point. Walking is not one number, it is a family of speeds with different energy costs.

The same applies everywhere in the catalogue. Resistance training at 8 to 15 reps is 3.5 MET under code 02054, while power lifting and body building at vigorous effort is 6.0 under code 02050. Choosing between them is choosing between two published measurements, not between two adjectives.

The formula, worked line by line

The formula people quote is MET times 3.5 times kilograms divided by 200, and written that way the 200 looks arbitrary. It is not. It falls out of two physiological constants and a unit conversion, and once you have seen the derivation the whole method stops being a black box.

The first constant is the definition of a MET. One metabolic equivalent is a rate of oxygen consumption of 3.5 millilitres per kilogram of body mass per minute, the convention for a body at rest. An activity rated at 4.8 MET is one that consumes oxygen 4.8 times as fast.

The second constant is the caloric equivalent of oxygen. Burning fuel with oxygen releases roughly 5 kilocalories per litre of oxygen consumed. The exact figure moves with what is being burned, close to 4.7 on fat and around 5.05 on carbohydrate, and 5 is the round middle the convention adopts.

Put them together and every step is a unit conversion. Multiply the MET by 3.5 and by body mass to get millilitres of oxygen a minute. Divide by 1,000 for litres. Multiply by 5 for kilocalories. Dividing by 1,000 and multiplying by 5 is dividing by 200, which is where the mystery number comes from.

1 MET     = 3.5 mL O2 per kg per minute
1 litre O2 releases about 5 kcal

mL O2/min = MET x 3.5 x kg
L O2/min  = MET x 3.5 x kg / 1000
kcal/min  = MET x 3.5 x kg x 5 / 1000  =  MET x 3.5 x kg / 200

gross kcal   = kcal/min x minutes
resting kcal = 1 x 3.5 x kg / 200 x minutes
net kcal     = (MET - 1) x 3.5 x kg / 200 x minutes

Where the method stops being reliable

The derivation is exact. What goes into it is not, and it is worth being precise about which part is soft. The 3.5 and the 5 are conventions. The MET value is a measurement made on other people. Your weight and your minutes are the only two numbers on the page that are actually about you.

That ordering explains why two people can do the same thing for the same time at the same weight and genuinely differ. Efficiency of movement, training state, terrain, temperature and how hard you chose to work all sit inside the single MET value, which cannot see any of them.

One last practical note. Because the resting share is a flat rate per minute, it is a bigger fraction of a gentle activity than an intense one. At 2.3 MET it is 43 percent of the reported total, at 4.8 MET it is 21 percent, and at 11 MET it is 9 percent. That is why the net line matters most for the gentlest entries.

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