30-day cost
$53.11
Daily cost
$1.77
Cooling-season cost
$212.43
Annual cost
$646.14
Estimated input power
1,200 W
One useful next step
Use measured kWh or a compatible label value when available, then compare options only when capacity and service are comparable.
Cooling systems cycle or vary speed. Clock runtime can differ from full-load-equivalent runtime, and weather, setpoint, humidity, sizing, insulation, and controls affect use.
How AC Electricity Cost Is Calculated
Cost = (Wattage ÷ 1,000) × Hours Used × Electricity Rate per kWh
Wattage divided by 1,000 gives kilowatts. Multiply by full-load-equivalent hours and the electricity rate to estimate cost. For the entered 1,200-watt and 8-hour scenario, the daily estimate is $1.77 and the 30-day estimate is $53.11.
AC runtime is not always continuous full-power runtime. Single-stage equipment cycles on and off; variable-speed and inverter equipment can run longer at lower power. Weather, setpoint, sizing, insulation, humidity, and equipment controls affect duty cycle. Use measured average power, an EnergyGuide annual-kWh figure, or full-load-equivalent hours when available.
Do not compare a window unit and a central system on input power alone: they may cool different areas and deliver different capacity.
Frequently Asked Questions
How much does it cost to run a window AC for 8 hours?
At the U.S. average electricity rate of $0.18/kWh, a 1,200-watt window air conditioner costs $1.77 to run for 8 hours. A 500-watt unit costs about $0.74, and a 1,500-watt unit costs about $2.21.
Is it cheaper to run a window AC or central air?
For the entered examples, 1,200W and 3,500W have different input costs while operating. They also provide different capacity and coverage, so the result is not a like-for-like system comparison or a universal winner.
How much does central AC cost to run per month?
A 3,500-watt central AC running 8 hours per day at the U.S. average rate of $0.18/kWh costs about $5.16/day or approximately $154.90/month during summer.
Does running a fan with the AC save money?
A fan uses electricity for airflow and an AC removes heat and moisture. A fan may support comfort in some conditions, but the services are not identical and this calculator does not promise a fixed savings amount.
What size window AC do I need for my room?
Use the manufacturer's sizing guidance and account for room area, ceiling height, sun, occupancy, insulation, climate, and moisture load. Input watts do not determine cooling capacity by themselves.