Gross calories come from the ACSM metabolic equations, the standard used by exercise physiologists to estimate oxygen cost from treadmill speed and grade. Below 5 mph the console uses the walking equation; at 5 mph and above (or when a segment is set to Run), it uses the running equation. Each converts speed and incline into VO₂ (ml/kg/min), then into calories using your body weight.

Net calories subtract your personal resting metabolic rate for the same duration, calculated with the Mifflin–St Jeor equation from your age, sex, height, and weight — so net reflects calories burned above what you'd burn sitting still.

Bicep curls don't have an official clinical equation for concurrent treadmill use, so the console models them as two extra costs, both counted only for the minutes you're actually curling: the dumbbell's weight is added to your body weight in the treadmill formula above, since your legs are carrying that extra load while you curl; and a MET-based estimate for the muscular effort of actively flexing the biceps (roughly 2–6 METs, in line with light-to-vigorous resistance training in the Compendium of Physical Activities), with only the effort above resting counted to avoid double-counting your baseline metabolism. You can set curling time separately from segment duration — for example, 2 minutes of curls inside a 3-minute segment — and only that portion carries the extra weight or the arm-work bonus.

This gives a well-grounded estimate, not a lab measurement — actual burn varies with fitness level, running economy, and form. Net calories are floored at zero.