How the calculator works. Walking and running use the ACSM oxygen-cost equations (speed, grade and bodyweight), scaled by one calibration factor per activity fitted to the measured rows here: 0.84 for walking, 0.74 for running, 0.71 for stair climbing. The bike uses the ACSM cycling equation straight from watts, with no calibration row in the sheet to check it against; watts already measure the work, so bodyweight matters little there. Holding the rail removes about half of the incline work; that is what the 15% rows show. A weighted vest counts as bodyweight. The curved treadmill costs about 1.4 times a motorised walk at the same speed. Where the model and the measured column disagree by more than 10 percent, the 5% and 10% incline rows, the sheet's own rows are inconsistent with each other; the model sits between them. All figures are gross. The log's net figure subtracts roughly 1 kcal per minute of resting burn. Steps: 10,000 steps at 72 kg is 236 kcal.