Cost to run

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.

Reviewed 2026-07-15 · methodology appliance-energy-1.0.0 · data vintage 2026-04-ytd

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	Monthly range	Most likely/year
Evenings only	4 hours each evening in a small bedroom	59.40	$6.33–$14.12	$116.21
Day and evening	8 hours a day in a medium room	158.40	$16.87–$37.66	$309.89
Nearly continuous	16 hours a day during a hot month	436.80	$46.53–$103.84	$854.56

Source: U.S. Energy Information Administration, Electric Power Monthly Table 5.6.B. Data vintage 2026-04-ytd. State-average pricing is not your exact utility tariff.

Calculate your own usage

Your inputs

ZIP code

Used to pick your state’s average electricity rate. We don’t need your street address.

ApplianceHow manyHours used per day (optional)

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Rated watts (from the appliance label)Duty cycle (0–1; share of time drawing full power)Days per month

Your estimate — a range, confidence level, and the sources behind it — will appear here.

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?

For cooling a single room, usually yes, because it conditions less space. Cooling several rooms with multiple window units can approach or exceed central AC cost.

What does the energy-saver mode change?

Energy-saver mode turns the fan off with the compressor instead of running it continuously, which lowers the effective duty cycle you should enter.

Do inverter window units change this estimate?

Inverter models vary compressor speed instead of switching on and off, so their average draw can sit well below rated watts. Use a measured average when you have one.

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