Estimate the cost to run a gas or electric hob.
Hob running cost is the burner rating multiplied by the hours used and by the average power setting, which matters because almost nobody cooks on full power for the whole time. Efficiency then determines how much of that energy reaches the food rather than the room. Induction couples directly into the pan base and lands around 85 percent. Ceramic and radiant elements must heat a glass surface first, giving roughly 70 percent. A gas burner sends most of its flame around the sides of the pan and manages only about 40 percent, so gas needs to be well under half the price of electricity per kilowatt-hour to break even on delivered heat.
Energy consumed
kWh = burner kW x (minutes / 60) x average power setting%
Useful heat
Useful kWh = consumed kWh x efficiency
Per kilowatt-hour of fuel, usually yes. Per kilowatt-hour of heat delivered into the pan, often not — gas is around 40 percent efficient against induction's 85, so gas needs to cost less than about half as much per unit just to draw level. Compare delivered heat, not fuel price.
Because the burner rating is its maximum. Most cooking is a short burst at high power to boil, then a long simmer at 20 to 40 percent. Assuming full power throughout can overstate the cost twofold. A rough average across the whole cook is far more accurate.