How Much Electricity Does a Window Air Conditioner Use?
Calculate window air conditioner electricity usage (kWh) and monthly cooling cost based on BTU capacity (5,000–12,000), EER/CEER rating, and thermostat duty cycle.
Key Takeaways & Core Facts
- Small 5,000 BTU window AC units draw 450W to 550W, while large 12,000 BTU units draw 1,000W to 1,200W when the compressor is actively running.
- Operating an 8,000 BTU window unit for 8 hours daily at a 60% compressor duty cycle consumes ~3.5 kWh/day ($16.00 to $32.00 monthly).
- CEER (Combined Energy Efficiency Ratio) ratings of 12.0+ consume 10% to 15% less electricity than older units with EER ratings below 10.0.
Direct Answer: Window AC Power & Monthly Cooling Cost
A window air conditioner consumes between 450W and 1,200W of electrical power depending on cooling capacity (5,000 BTU to 12,000 BTU) and CEER energy efficiency rating.
Running an 8,000 BTU window AC for 8 hours daily at a 60% compressor duty cycle consumes approximately 3.5 kWh per day (105 kWh per month), costing between $16.00 and $32.00 per month at 15 ¢ to 30 ¢/kWh electric rates.
BTU Capacity, CEER Rating & Compressor Duty Cycle
Window AC electrical consumption is governed by four key variables:
- BTU Cooling Capacity: 5,000 BTU (150 sq ft) draws ~450W; 8,000 BTU (350 sq ft) draws ~700W; 12,000 BTU (550 sq ft) draws ~1,100W.
- CEER Efficiency Rating: Combined Energy Efficiency Ratio (CEER) measures BTU cooling output per Watt-hour input. ENERGY STAR certified units (CEER 12.0+) use 10% to 15% less energy than standard models.
- Compressor Duty Cycle: Once a room reaches setpoint temperature, the compressor cycles off, leaving only the fan running (30W–50W). Average summer duty cycles range from 50% to 70%.
- Thermostat Settings: U.S. DOE testing indicates raising the thermostat setting by 4°F (e.g., from 72°F to 76°F) reduces cooling energy consumption by 10% to 15%.
Window AC Monthly Costs across Sizes & Utility Rates
| Unit Size (BTU/hr) | Rated Input Watts | Monthly kWh | Cost at 15 ¢/kWh | Cost at 20 ¢/kWh | Cost at 30 ¢/kWh |
|---|---|---|---|---|---|
| Small 5,000 BTU (Bedroom) | 450W | 64.8 kWh | $9.72 | $12.96 | $19.44 |
| Medium 8,000 BTU (Living Room) | 720W | 103.7 kWh | $15.55 | $20.74 | $31.11 |
| Large 12,000 BTU (Open Concept) | 1,100W | 158.4 kWh | $23.76 | $31.68 | $47.52 |
* Note: Calculations assume 8 hours daily operating time at a 60% compressor duty cycle. Figures represent typical manufacturer benchmarks and illustrative assumptions.
Assumptions & Sizing Recommendations
Undersized window AC units run continuously without reaching target temperature, while oversized units cool quickly without dehumidifying properly.
Calculate your exact room cooling expenses with our dedicated AC Cost Calculator or evaluate central air power in our Air Conditioner Cost Guide.
Air Conditioner Cost Calculator
Estimate window air conditioner cooling expenses based on BTU capacity, CEER rating, and daily runtime.
Calculate Window AC Cooling Cost →Government & Official Data Sources
- ENERGY STAR — Room Air Conditioners Energy Efficiency Specification (CEER efficiency baselines, cooling capacity in BTU/hr, and compressor energy limits)
- U.S. Department of Energy — Room Air Conditioner Energy Saver Guide (Sizing window AC units by room square footage, thermostat settings, and seasonal energy use)