Window vs portable air conditioner: which costs more to run?
Watts and running cost for a window unit and a portable unit, worked out from the capacity and CEER on their labels and your state's average electricity price.
Short answer
At the federal minimum efficiency for each type, an 8,000 Btu/h window air conditioner draws about 500 watts while cooling and a portable unit of the same rated capacity about 1,108 watts, more than twice as much. Cooling 8 hours a day for 30 days at the US average electricity price for July 2026, that's $21.97 for the window unit against $48.69 for the portable.
Work out your own cost
Window against portable, state by state
The example compares an 8,000 Btu/h window unit at CEER 16.0, the federal minimum for most window units of that size made from May 26, 2026, with an 8,000 Btu/h portable unit at its own federal minimum, CEER 7.22. Both cool 8 hours a day. Swap in the figures from the labels of the models you're looking at.
| State | Price (¢/kWh) | Window, 30 days | Portable, 30 days | Difference |
|---|---|---|---|---|
| Alabama | 16.40 | $19.68 | $43.61 | $23.93 |
| Alaska | 28.83 | $34.60 | $76.67 | $42.07 |
| Arizona | 15.38 | $18.46 | $40.90 | $22.44 |
| Arkansas | 14.33 | $17.20 | $38.11 | $20.91 |
| California | 33.61 | $40.33 | $89.38 | $49.05 |
| Colorado | 17.00 | $20.40 | $45.21 | $24.81 |
| Connecticut | 24.16 | $28.99 | $64.25 | $35.26 |
| Delaware | 18.48 | $22.18 | $49.14 | $26.97 |
| District of Columbia | 25.21 | $30.25 | $67.04 | $36.79 |
| Florida | 15.03 | $18.04 | $39.97 | $21.93 |
| Georgia | 16.27 | $19.52 | $43.27 | $23.74 |
| Hawaii | 48.00 | $57.60 | $127.65 | $70.05 |
| Idaho | 13.73 | $16.48 | $36.51 | $20.04 |
| Illinois | 19.22 | $23.06 | $51.11 | $28.05 |
| Indiana | 16.73 | $20.08 | $44.49 | $24.41 |
| Iowa | 15.99 | $19.19 | $42.52 | $23.33 |
| Kansas | 15.27 | $18.32 | $40.61 | $22.28 |
| Kentucky | 13.81 | $16.57 | $36.72 | $20.15 |
| Louisiana | 12.72 | $15.26 | $33.83 | $18.56 |
| Maine | 32.41 | $38.89 | $86.19 | $47.30 |
| Maryland | 21.41 | $25.69 | $56.94 | $31.24 |
| Massachusetts | 30.49 | $36.59 | $81.08 | $44.49 |
| Michigan | 23.05 | $27.66 | $61.30 | $33.64 |
| Minnesota | 17.45 | $20.94 | $46.40 | $25.46 |
| Mississippi | 14.54 | $17.45 | $38.67 | $21.22 |
| Missouri | 16.09 | $19.31 | $42.79 | $23.48 |
| Montana | 14.99 | $17.99 | $39.86 | $21.87 |
| Nebraska | 13.78 | $16.54 | $36.64 | $20.11 |
| Nevada | 12.77 | $15.32 | $33.96 | $18.64 |
| New Hampshire | 26.60 | $31.92 | $70.74 | $38.82 |
| New Jersey | 25.19 | $30.23 | $66.99 | $36.76 |
| New Mexico | 16.09 | $19.31 | $42.79 | $23.48 |
| New York | 29.90 | $35.88 | $79.51 | $43.63 |
| North Carolina | 15.16 | $18.19 | $40.31 | $22.12 |
| North Dakota | 13.41 | $16.09 | $35.66 | $19.57 |
| Ohio | 19.45 | $23.34 | $51.72 | $28.38 |
| Oklahoma | 14.35 | $17.22 | $38.16 | $20.94 |
| Oregon | 15.97 | $19.16 | $42.47 | $23.30 |
| Pennsylvania | 21.72 | $26.06 | $57.76 | $31.70 |
| Rhode Island | 28.29 | $33.95 | $75.23 | $41.28 |
| South Carolina | 15.47 | $18.56 | $41.14 | $22.58 |
| South Dakota | 15.37 | $18.44 | $40.87 | $22.43 |
| Tennessee | 13.71 | $16.45 | $36.46 | $20.01 |
| Texas | 15.88 | $19.06 | $42.23 | $23.17 |
| Utah | 13.12 | $15.74 | $34.89 | $19.15 |
| Vermont | 23.75 | $28.50 | $63.16 | $34.66 |
| Virginia | 17.55 | $21.06 | $46.67 | $25.61 |
| Washington | 14.71 | $17.65 | $39.12 | $21.47 |
| West Virginia | 15.78 | $18.94 | $41.96 | $23.03 |
| Wisconsin | 19.06 | $22.87 | $50.69 | $27.81 |
| Wyoming | 14.36 | $17.23 | $38.19 | $20.96 |
| US average | 18.31 | $21.97 | $48.69 | $26.72 |
From Btu to watts
Room and portable air conditioners are rated by cooling capacity in British thermal units per hour and by the combined energy efficiency ratio, CEER, in Btu per watt-hour. Dividing one by the other gives the power the unit draws while it cools.
watts ≈ capacity (Btu/h) ÷ CEER (Btu/Wh)
cost ($) = watts ÷ 1,000 × hours × days × price (¢ per kWh) ÷ 100
Worked example: 8,000 ÷ 16.0 = 500 watts for the window unit, and 8,000 ÷ 7.22 = 1,108 watts for the portable. Over 8 hours a day for 30 days, that's 120 kWh against 265.9 kWh: $21.97 against $48.69 at the US average of 18.31 cents.
The result is an approximation that errs slightly high. The Department of Energy's test procedures build CEER from the energy used in cooling mode plus the energy used in standby and off modes, spread over 750 hours of cooling a year. Dividing capacity by CEER therefore counts a little standby power on top of the cooling draw.
Why portables come out higher
The federal rules ask far less of portable units. Under 10 CFR 430.32(b)(2), window units without reverse cycle and with louvered sides, rated 8,000 to 13,900 Btu/h and made from May 26, 2026, need a CEER of at least 16.0. The rule they replace, in force from June 1, 2014, required 10.9 for that size band, and units made before the change can still be on sale: at 10.9, the example window unit would draw 734 watts. Portable units made on or after January 10, 2025 follow a formula, 1.04 × SACC ÷ (3.7117 × SACC0.6384), which gives the minimums below.
| SACC | Minimum CEER (Btu/Wh) | Capacity ÷ CEER |
|---|---|---|
| 8,000 Btu/h | 7.22 | 1,108 W |
| 10,000 Btu/h | 7.83 | 1,277 W |
| 12,000 Btu/h | 8.37 | 1,434 W |
| 14,000 Btu/h | 8.85 | 1,582 W |
The two capacities are not measured the same way. A portable's SACC, seasonally adjusted cooling capacity, is defined in DOE's test procedure as the cooling delivered to the room under the test conditions, with heat from the hose and from outside air drawn into the room counted against it, and with results at 95°F and 83°F weighted 20% and 80%. A window unit is tested under a separate procedure. The two numbers are close enough to compare running costs, but not identical measures.
Reading the yellow label
Room and portable air conditioners carry the Federal Trade Commission's EnergyGuide label. Under 16 CFR 305.18, its estimated yearly cost assumes a national average electricity price and “a seasonal use of 8 hours use per day over a 3-month period”. The price the FTC sets for these labels is 13 cents per kWh. In EIA's July 2026 table, only Louisiana and Nevada averaged less than that, so in most states the dollar figure on the label understates what the same use would cost at the state's average price. Type the label's capacity and CEER into the calculator with your state selected to reprice it.
What the state price is
The prices are the residential averages in the US Energy Information Administration's Electric Power Monthly, Table 5.6.A, for July 2026, marked as preliminary. EIA's next release is due on October 23, 2026.
Sources
- U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A: Average Price of Electricity to Ultimate Customers by End-Use Sector, by State, July 2026 and 2025, residential column. Data for July 2026, released September 24, 2026; next release October 23, 2026. Read October 1, 2026.
- Electronic Code of Federal Regulations, 10 CFR 430.32, Energy and water conservation standards and their compliance dates, paragraphs (b), room air conditioners, and (cc), portable air conditioners, including the portable air conditioner CEER formula. Read October 1, 2026.
- Electronic Code of Federal Regulations, Appendix F to Subpart B of Part 430: Uniform Test Method for Measuring the Energy Consumption of Room Air Conditioners, sections 2.9 and 5.2. Read October 1, 2026.
- Electronic Code of Federal Regulations, Appendix CC to Subpart B of Part 430: Uniform Test Method for Measuring the Energy Consumption of Portable Air Conditioners: SACC definition and weighting, 750 cooling-mode hours. Read October 1, 2026.
- Electronic Code of Federal Regulations, 16 CFR Part 305, Energy Labeling Rule: section 305.18 (room and portable air conditioner labels) and Appendix K2 (13 cents per kWh). Read October 1, 2026.
Changes: first published October 1, 2026.