Fictional worked example

Air conditioning during an eight-hour window

A bedroom AC is switched on overnight for eight hours. A sample plug meter log separates the compressor’s active time from its scheduled window.

Inputs and calculation

Compressor active half the window
Tool input	Value
Currency	USD
Power unit	W
Power	1500
Hours per day	8
Days or equivalent sessions	30
Duty cycle (%)	50
Energy price (USD per input kWh)	0.25

1500 ÷ 1,000 × 8 × 30 × 50% = 180 kWh. 180 × 0.25 rounds to USD 45.00.

Tool result · USD 45.00

Compressor active three quarters
Tool input	Value
Currency	USD
Power unit	W
Power	1500
Hours per day	8
Days or equivalent sessions	30
Duty cycle (%)	75
Energy price (USD per input kWh)	0.25

1500 ÷ 1,000 × 8 × 30 × 75% = 270 kWh. 270 × 0.25 rounds to USD 67.50.

Tool result · USD 67.50

Keeping the same timer can still raise the bill by 22.50 if the compressor runs longer.

The duty-cycle approximation assumes the remaining draw is negligible. A variable-speed unit is better modeled with measured average watts.