How this calculator works
A MET is a multiple of resting metabolic rate. One MET is about 3.5 mL of oxygen per kilogram per minute, and one litre of oxygen releases roughly 5 kcal. The Compendium of Physical Activities lists cycling at several paces, from leisure riding at 4 METs to racing above 30 km/h at 15.8 METs. The estimate is gross energy use, including the energy you would have burned at rest. Power meters offer a more direct route: mechanical work at the pedals divided by gross metabolic efficiency, typically about 24 percent for cycling, gives metabolic energy.
Formula
From METs: kcal = MET x 3.5 x body mass (kg) / 200 x minutes. From power: mechanical joules = watts x seconds. Gross kcal = mechanical joules / (4,184 x 0.24). Equivalent fat = kcal / 7,700.
Worked example
A 75 kg rider at a moderate 8 METs for one hour: 8 x 3.5 x 75 / 200 x 60 = 630 kcal. At 200 W for the same hour, mechanical work is 720 kJ, and gross energy is 720 / 0.24 = 3,000 kJ, which is 717 kcal. Both routes put the ride in the low 600 to 700 kcal range.
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Frequently asked questions
Why do power meter calories differ from the MET estimate?
A power meter measures the work actually delivered to the drivetrain, then estimates the metabolic cost from an assumed efficiency. The MET table describes an average rider at a given speed, so wind, hills and drafting can make the two disagree.
Is the fat equivalent the same as weight lost?
No. Burning 7,700 kcal of stored fat is equivalent to about one kilogram, but body mass also changes with glycogen, water, food and appetite. Use the figure as a scale, not a prediction.
Should I subtract resting calories?
The MET values are gross, so they already include resting energy for the same period. If you want the extra cost of cycling rather than total energy use, subtract about one MET for the same duration.