How much does a window AC unit cost to run?
A window air conditioner cools one room, so its cost depends on the unit's wattage, the hours you keep it on, and how often its compressor cycles against the heat coming into that room.
Content reviewed 2026-09-27 · Rates published 2026-09-24 · methodology appliance-energy-1.0.0 · data vintage 2026-07-ytd
Using the day and evening assumptions below, electricity costs about $0.85 per day of use and $25.44 for 30 days of use at the Texas average rate. Adjust the calculator for your equipment and schedule.
Example costs using the Texas state-average rate
These are generated examples for a consistent location. Enter your own ZIP and usage below for a more relevant state-average estimate.
| Scenario | Assumption | kWh/month | Cost/day of use | Monthly range | Cost at 365 days/year |
|---|---|---|---|---|---|
| Evenings only | 4 hours each evening in a small bedroom 900 W × 4 h/day × 0.55 duty × 30 days × 1 unit(s) | 59.40 | $0.32 | $6.32–$14.10 | $116.07 |
| Day and evening | 8 hours a day in a medium room 1100 W × 8 h/day × 0.6 duty × 30 days × 1 unit(s) | 158.40 | $0.85 | $16.85–$37.61 | $309.51 |
| Nearly continuous | 16 hours a day during a hot month 1300 W × 16 h/day × 0.7 duty × 30 days × 1 unit(s) | 436.80 | $2.34 | $46.47–$103.71 | $853.49 |
Wattage, runtime and duty cycle below are illustrative assumptions, not measurements of a particular model. Annual figures assume use on all 365 days; monthly figures use each scenario's stated number of days.
Source: U.S. Energy Information Administration, Electric Power Monthly Table 5.6.B. Data vintage 2026-07-ytd. State-average pricing is not your exact utility tariff.
What does one use cost?
Capacity in BTU/h is cooling output, not electrical input. These examples assume an EER of 10 BTU/Wh, so input watts = BTU/h / 10, then assume eight hours with a 60% duty cycle. They are not product specifications or room-sizing recommendations; use your model's rated watts.
| Task | Assumptions | kWh/use | Estimated cost/use |
|---|---|---|---|
| 5,000 BTU/h example | EER 10 → 500 W × 8 h × 60% duty | 2.4000 | $0.39 Range $0.26–$0.57 |
| 6,000 BTU/h example | EER 10 → 600 W × 8 h × 60% duty | 2.8800 | $0.46 Range $0.31–$0.68 |
| 8,000 BTU/h example | EER 10 → 800 W × 8 h × 60% duty | 3.8400 | $0.62 Range $0.41–$0.91 |
Illustrative usage, priced at the same Texas state average as the calculator. Costs are rounded to cents; actual consumption and your utility price can differ.
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How window unit size changes cost
Window units commonly range from about 5,000 to 15,000 BTU per hour, and electrical draw rises with capacity. An oversized unit short-cycles and wastes energy on humid days, while an undersized one runs almost continuously, so the right size often costs less to operate.
Room conditions matter as much as the unit
Sun exposure through windows, poor seals around the chassis, uninsulated walls, and heat from electronics extend compressor runtime. Sealing the mounting gaps and closing curtains during peak sun are inexpensive ways to shorten the duty cycle you enter here.
Assumptions behind the window AC scenarios
Scenarios treat the unit as a single load at its rated watts with thermostat cycling represented by the duty-cycle input. The model does not estimate BTU sizing for your room, compare energy-efficiency ratios between models, or account for inverter units that vary compressor speed.
Frequently asked questions
Is a window AC cheaper to run than central air?
What does the energy-saver mode change?
Do inverter window units change this estimate?
Compare options and check your assumptions
Related appliance cost guides
- Central Air Conditioner Cost to Run per Month
- Portable Air Conditioner Cost to Run Monthly
- Box Fan Electricity Cost: Day, Night, Month
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