Two riders holding 120 watts for an hour: the 75 kg one spends 546 kcal, the 95 kg one 588. On a bike that gap stays small, and why it does is the whole point of this page.
Estimates are for general guidance only and are not medical advice. For a personalised plan, book a free guided tour at RPM Gym.
An hour lands between roughly 450 and 785 kcal for a 60 to 95 kg rider averaging 100 to 180 W. Your own figure is the number above. The band printed next to it is ±15% and it is not decoration.
Rearrange the equation and the result splits cleanly in two: kcal = 0.054 × watts × minutes, plus 0.035 × kilograms × minutes. The first term is the work you did against the machine, and your bodyweight does not appear in it anywhere. The second is what it costs to be a body of your size for that long, whatever the flywheel is doing.
So take 150 W for half an hour. A 60 kg rider is charged 306 kcal and a 90 kg rider 338. Both paid exactly 243 for the pedalling — the same number, to the kilocalorie. What separates them is 63 against 94 for existing. A 1.5× difference in bodyweight has bought a 1.1× difference in energy.
A MET table answers that differently, and not by a rounding error. Take the 7.5 MET the hub burn calculator uses for cycling, multiply by bodyweight, and the same two rides come out at 236 and 354 — a 1.5× gap, because that model makes every calorie proportional to mass. On a treadmill it would be roughly right, since you are carrying yourself. On an ergometer the machine has already fixed the work rate, and mass sits in the denominator of the published equation rather than the numerator.
One rule to carry out of here: an hour on a bike costs about 3.24 kcal for every watt you average, plus about 2.1 kcal for every kilogram you weigh. At 120 W and 75 kg that is 389 plus 158, which is the 546 above. The watts term does most of the work, and it is also the only one of the two you can train.
VO2 (mL/kg/min) = (10.8 × watts ÷ body weight kg) + 7 kcal = VO2 × body weight kg ÷ 1000 × 5 kcal per litre of oxygen × minutes Which reduces to: kcal = (10.8 × watts + 7 × kg) × 5 × minutes ÷ 1000 The + 7 is 3.5 mL/kg/min for rest plus 3.5 for turning the pedals against no resistance.
An 82 kg rider holds an average of 165 W for 45 minutes on a gym bike.
530 kcal for the session, 451 to 610 once the error band is honoured, and 707 had the rider held that power for a full hour. Add 20 kg to the rider and the ride costs 562: six percent more energy for twenty-four percent more body. Everything the pedals demanded stayed at 401.
Roughly 450 to 785 kcal for a 60 to 95 kg rider averaging 100 to 180 W. In the middle of that, at 75 kg and 150 W, an hour comes to 644. Power moves the answer far more than mass does: hold 150 W and going from 60 kg to 95 kg only takes the hour from 612 to 686.
Then this page has nothing honest to offer, and it will not invent something. Cycling has no published speed equation of the kind walking and running have, and the lookup table that would replace one could not be verified here. Most gym bikes do report power somewhere on the console. Outdoors with no meter, a heart-rate estimate is the more defensible route.
Slightly more, not proportionally more. At 150 W for thirty minutes a 60 kg rider is charged 306 kcal and a 90 kg rider 338 — about ten percent apart for a fifty percent difference in mass. The extra is not the pedalling, which cost both of them 243. It is the larger body idling underneath it.
Because a MET is oxygen use per kilogram, and on a bike the machine sets the oxygen use while the kilograms are yours. The same 120 W hour reads 8.2 MET for a 60 kg rider and 5.7 for a 100 kg one. The ride is identical; its intensity relative to body size is not. That is the clearest sign a single fixed cycling MET was never going to describe two different riders.
Three usual candidates. The console may not know your weight, though on a bike that explains less than people expect — all of your mass contributes is 158 kcal of a 546 kcal hour. It may be showing work rather than energy, and 432 kJ at the pedals is a different quantity from the kilocalories you spent. Or it may be netting off resting expenditure, which this page does not.
For this equation, yes. The work term is linear, so 20 minutes at 90 W and 20 at 210 W is charged exactly the same as 40 minutes steady at 150. Your body does not treat those as one session, and none of that difference reaches this number. It is the honest limit of feeding an average into a linear model.
The equation keeps returning numbers and the tool flags that it is extrapolating. A 75 kg rider gets 806 kcal for an hour at 200 W and 968 at 250 W, and the second is the published relationship working beyond where it was anchored. Useful for comparing one hard ride against another, not for logging against food.
Holding a higher average power over the same hour is a leg strength question as much as an aerobic one. Work on both at RPM Gym in Al Manhal — book a free guided tour.