Typical air conditioner power
Small window units may draw roughly 500 to 900 watts while larger window or portable units can draw 1,000 to 1,500 watts or more. Central systems often use several thousand watts across the compressor and indoor fan. Use electrical input power—not BTU cooling capacity—as the calculator input.
Example: a 1,200W unit for eight hours
At a 17¢ electricity rate, 1.2 kW running for eight hours uses 9.6 kWh and costs about $1.63 per day or $48.96 for 30 similar days. A compressor that cycles off part of the time can use less.
Runtime matters more than the thermostat display
The calculator's hours field represents equivalent full-power hours. If an AC is available for eight hours but its compressor operates about half the time, four equivalent hours may be a better estimate. Inverter equipment can vary its power rather than simply switching on and off.
Ways to lower cooling cost
- Clean filters and keep outdoor coils unobstructed.
- Use blinds or exterior shade during peak sun.
- Seal air leaks and avoid cooling unused rooms.
- Compare input watts and efficiency ratings when replacing equipment.
Air conditioner FAQ
Can I enter the BTU rating as watts?
No. BTU per hour describes cooling output. Use the unit's electrical input watts or amperage and voltage information.
Does a central AC run at full power all day?
Usually not. It cycles or modulates according to load, weather, equipment size, and thermostat settings.
Why is my bill increase larger than this estimate?
Hot weather can also increase fan use, dehumidification, and total runtime. Utility taxes, tiers, and other household loads are outside this single-appliance estimate.