How to use this calculator
Enter electrical input watts from your AC label, not its cooling output in BTU/h. Choose daily scheduled hours and an estimated average power fraction. Inverter units vary power continuously; fixed-speed units cycle on and off.
The formula
Monthly kWh = input W ÷ 1,000 × hours/day × duty% ÷ 100 × days. Cost = monthly kWh × rate.
Worked example
A 1,200 W AC scheduled 8 hours daily at 65% average power uses 6.24 kWh per day. In 30 days it uses 187.2 kWh and costs 29.95 at a sample rate of 0.16. One fewer hour per day saves about 3.74 in energy charges.
Assumptions and limitations
Weather, insulation, occupancy, thermostat and room size affect actual draw. This tool does not infer savings from changing thermostat temperature. The one-hour comparison keeps the same average power and cannot reduce usage below zero.
Frequently asked questions
Can I enter 12,000 BTU as watts?
No. BTU/h is cooling output, while this calculator needs electrical input watts. Look for rated input or measured average consumption.
What duty cycle should I use for an inverter AC?
Use measured average watts with 100%, or estimate average consumption as a fraction of the rated input. A default such as 65% is only an example, not a universal inverter efficiency.
Estimates only. Use your utility tariff and appliance energy label for more accurate inputs.