How this calculator works
A MET is a multiple of resting metabolism: one MET is about 3.5 millilitres of oxygen per kilogram per minute, and a litre of oxygen releases roughly 5 kilocalories. The 2011 Adult Compendium of Physical Activities gives different values for different kinds of resistance work. Varied training at 8 to 15 reps is 3.5 METs (code 02054), heavy squats or deadlifts are 5.0 (02052), vigorous powerlifting or body building is 6.0 (02050), a reciprocal-superset circuit is 5.8 (02055), general body weight work is 3.0 (02056), high-intensity body weight work is 6.5 (02057), and a kettlebell circuit with minimal rest is 7.5 (02040). The calculator multiplies the chosen MET, body mass and session time to estimate gross energy use.
Formula
kcal per minute = MET x 3.5 x body mass (kg) / 200. Total calories = kcal per minute x minutes. Equivalent body fat in kilograms = total calories / 7,700.
Worked example
A 75 kg person trains for 60 minutes with varied resistance at 3.5 METs: 3.5 x 3.5 x 75 / 200 = 4.59 kcal/min, or 275.6 kcal for the session. The same hour of vigorous powerlifting at 6.0 METs is 7.88 kcal/min, or 472.5 kcal. A 90 kg person doing 45 minutes of heavy squats and deadlifts at 5.0 METs burns 354.4 kcal.
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Frequently asked questions
Why does the lifting style change the estimate so much?
The Compendium separates resistance work by effort and structure. Heavy compound lifts and vigorous body building use more energy per minute than light, varied training with long pauses, so the MET values range from 3.0 to 7.5.
Does the estimate include rest between sets?
The equation applies one MET value to the whole session time you enter. The Compendium values describe the activity period, not a long rest. If your session includes extended conversations or long pauses, the true average will be lower than the estimate.
Should I subtract calories I would have burned at rest?
The MET values are gross, so the total already includes resting energy for the same period. Subtract about one MET if you want only the extra cost of training.
Is the fat equivalent the same as fat lost?
No. It is a scale that equates the estimated energy with stored fat, not a prediction of body mass change. Food, water, glycogen and appetite all affect real weight over time.