The short answer
Run an efficient 8,000 BTU window AC — the inverter class we recommend — for 8 hours a day and the national-average electric bill impact is $24 a month at May 2026 rates. A budget unit doing the same job costs about $32 a month. Where you live changes that more than any spec: the identical efficient unit costs $16/month in Idaho and $67/month in Hawaii — a 4.2× spread on electricity price alone.
Every number below is computed from the U.S. Energy Information Administration’s May 2026 average residential electricity rates — the latest available federal data — using the transparent method in the next section. No estimates, no “typical bill” hand-waving.
How we computed it (check our math)
The model: an 8,000 BTU unit at CEER 15 (the efficient inverter tier — e.g. the LG LW8022IVSM or Dreo U-Shaped) draws 8,000 ÷ 15 ≈ 533 watts while cooling. At 8 hours a day for 30 days that is 128 kWh a month. The budget tier at CEER 11 (the $150–250 class in our under-$300 guide) draws ≈727 watts — 174.5 kWh for the same cooling. Multiply by your state’s average residential rate from EIA’s Electric Power Monthly (Table 5.6.A, May 2026) and you get the figures below. What CEER actually measures is in our efficiency-ratings explainer; personalize the hours and rate with the cost calculator.
The 10 most expensive states to run an AC
1. Hawaii — $67/mo: at 52.00¢/kWh, a budget unit runs $91/month.
2. California — $43/mo: at 33.25¢/kWh, a budget unit runs $58/month.
3. New York — $38/mo: at 29.93¢/kWh, a budget unit runs $52/month.
4. Rhode Island — $38/mo: at 29.46¢/kWh, a budget unit runs $51/month.
5. Massachusetts — $37/mo: at 28.82¢/kWh, a budget unit runs $50/month.
6. Maine — $37/mo: at 28.63¢/kWh, a budget unit runs $50/month.
7. Alaska — $36/mo: at 28.23¢/kWh, a budget unit runs $49/month.
8. Connecticut — $35/mo: at 27.37¢/kWh, a budget unit runs $48/month.
9. New Hampshire — $35/mo: at 27.33¢/kWh, a budget unit runs $48/month.
10. District of Columbia — $33/mo: at 25.40¢/kWh, a budget unit runs $44/month.
The 10 cheapest states
1. Idaho — $16/mo: at 12.35¢/kWh, even a budget unit is only $22/month.
2. Utah — $17/mo: at 12.96¢/kWh, even a budget unit is only $23/month.
3. Oklahoma — $17/mo: at 13.38¢/kWh, even a budget unit is only $23/month.
4. Nebraska — $17/mo: at 13.59¢/kWh, even a budget unit is only $24/month.
5. Nevada — $17/mo: at 13.60¢/kWh, even a budget unit is only $24/month.
6. North Dakota — $17/mo: at 13.61¢/kWh, even a budget unit is only $24/month.
7. Missouri — $18/mo: at 13.68¢/kWh, even a budget unit is only $24/month.
8. New Mexico — $18/mo: at 14.12¢/kWh, even a budget unit is only $25/month.
9. Iowa — $18/mo: at 14.14¢/kWh, even a budget unit is only $25/month.
10. Louisiana — $18/mo: at 14.15¢/kWh, even a budget unit is only $25/month.
Every state, A to Z
Efficient = 8,000 BTU at CEER 15 (128 kWh/month at 8 h/day); budget = CEER 11 (174.5 kWh/month). Rates are EIA average residential prices, May 2026.
Alabama: 16.77¢/kWh — about $21/month efficient, $29/month budget.
Alaska: 28.23¢/kWh — about $36/month efficient, $49/month budget.
Arizona: 15.23¢/kWh — about $19/month efficient, $27/month budget.
Arkansas: 14.36¢/kWh — about $18/month efficient, $25/month budget.
California: 33.25¢/kWh — about $43/month efficient, $58/month budget.
Colorado: 16.16¢/kWh — about $21/month efficient, $28/month budget.
Connecticut: 27.37¢/kWh — about $35/month efficient, $48/month budget.
Delaware: 19.38¢/kWh — about $25/month efficient, $34/month budget.
District of Columbia: 25.40¢/kWh — about $33/month efficient, $44/month budget.
Florida: 15.17¢/kWh — about $19/month efficient, $26/month budget.
Georgia: 15.84¢/kWh — about $20/month efficient, $28/month budget.
Hawaii: 52.00¢/kWh — about $67/month efficient, $91/month budget.
Idaho: 12.35¢/kWh — about $16/month efficient, $22/month budget.
Illinois: 23.85¢/kWh — about $31/month efficient, $42/month budget.
Indiana: 18.15¢/kWh — about $23/month efficient, $32/month budget.
Iowa: 14.14¢/kWh — about $18/month efficient, $25/month budget.
Kansas: 15.13¢/kWh — about $19/month efficient, $26/month budget.
Kentucky: 14.98¢/kWh — about $19/month efficient, $26/month budget.
Louisiana: 14.15¢/kWh — about $18/month efficient, $25/month budget.
Maine: 28.63¢/kWh — about $37/month efficient, $50/month budget.
Maryland: 21.77¢/kWh — about $28/month efficient, $38/month budget.
Massachusetts: 28.82¢/kWh — about $37/month efficient, $50/month budget.
Michigan: 22.01¢/kWh — about $28/month efficient, $38/month budget.
Minnesota: 16.95¢/kWh — about $22/month efficient, $30/month budget.
Mississippi: 16.16¢/kWh — about $21/month efficient, $28/month budget.
Missouri: 13.68¢/kWh — about $18/month efficient, $24/month budget.
Montana: 14.67¢/kWh — about $19/month efficient, $26/month budget.
Nebraska: 13.59¢/kWh — about $17/month efficient, $24/month budget.
Nevada: 13.60¢/kWh — about $17/month efficient, $24/month budget.
New Hampshire: 27.33¢/kWh — about $35/month efficient, $48/month budget.
New Jersey: 23.27¢/kWh — about $30/month efficient, $41/month budget.
New Mexico: 14.12¢/kWh — about $18/month efficient, $25/month budget.
New York: 29.93¢/kWh — about $38/month efficient, $52/month budget.
North Carolina: 15.09¢/kWh — about $19/month efficient, $26/month budget.
North Dakota: 13.61¢/kWh — about $17/month efficient, $24/month budget.
Ohio: 19.52¢/kWh — about $25/month efficient, $34/month budget.
Oklahoma: 13.38¢/kWh — about $17/month efficient, $23/month budget.
Oregon: 16.27¢/kWh — about $21/month efficient, $28/month budget.
Pennsylvania: 21.55¢/kWh — about $28/month efficient, $38/month budget.
Rhode Island: 29.46¢/kWh — about $38/month efficient, $51/month budget.
South Carolina: 16.18¢/kWh — about $21/month efficient, $28/month budget.
South Dakota: 15.73¢/kWh — about $20/month efficient, $27/month budget.
Tennessee: 14.47¢/kWh — about $19/month efficient, $25/month budget.
Texas: 16.44¢/kWh — about $21/month efficient, $29/month budget.
Utah: 12.96¢/kWh — about $17/month efficient, $23/month budget.
Vermont: 24.89¢/kWh — about $32/month efficient, $43/month budget.
Virginia: 17.61¢/kWh — about $23/month efficient, $31/month budget.
Washington: 14.95¢/kWh — about $19/month efficient, $26/month budget.
West Virginia: 16.80¢/kWh — about $22/month efficient, $29/month budget.
Wisconsin: 19.74¢/kWh — about $25/month efficient, $34/month budget.
Wyoming: 14.80¢/kWh — about $19/month efficient, $26/month budget.
How to shrink your number
Buy the efficient tier once, save every month: the CEER 15 inverter class costs $8.58/month less than budget units at the national average — more in coastal states — and pays back its premium in one to two seasons of daily use. See the inverter guide and our full cost-to-run guide for the payback math.
Size the room, not the fear: an oversized unit short-cycles and wastes power without dehumidifying. Sixty seconds with the BTU calculator prevents both. And if your state sits in the expensive ten, the efficiency premium is not optional — in Hawaii the budget-vs-efficient gap alone is $24 a month.
Featured units
Specs and running costs for the units referenced in this guide:
LG Dual Inverter LW8022IVSM
Dreo U-Shaped 8K DR-HAC002
Frigidaire Inverter FHWW084WD1
Frequently asked questions
How much does a window AC cost to run per month?
Nationally, about $24 a month for an efficient 8,000 BTU unit (CEER 15) running 8 hours a day at the May 2026 average residential rate of 18.44¢/kWh — or roughly $32 for a budget unit (CEER 11) doing the same job. Your state moves that number a lot: the same efficient unit costs $16 in Idaho and $67 in Hawaii.
How much does AC cost per month in California?
At California’s 33.25¢/kWh (May 2026), an efficient 8,000 BTU window unit at 8 hours a day costs about $43 a month; a budget unit costs about $58. Only Hawaii is more expensive.
How much does AC cost per month in Florida or Texas?
Less than the coasts: Florida’s 15.17¢/kWh works out to about $19/month efficient ($26 budget), and Texas’s 16.44¢/kWh to about $21/month ($29 budget) — though longer cooling seasons in both states mean more months of paying it.
Does an inverter window AC really lower the bill?
Yes — that is exactly the efficient-vs-budget gap in our table. A CEER 15 inverter uses about a quarter less electricity than a CEER 11 budget unit for the same cooling, which at the national average is roughly $8.58 a month. In a high-rate state like New York (29.93¢/kWh) the gap widens to about $14 a month.
Why is my actual bill different from these numbers?
Four honest reasons: your unit’s real duty cycle (a right-sized inverter idles at partial power once the room is cool), your hours (we model 8 a day), your unit’s CEER, and your utility’s exact rate — state averages hide big utility-to-utility spreads, and time-of-use plans charge more on summer afternoons. Use our calculator with your own rate for a personal number.
Not sure what size you need?
Our calculator factors in climate, sun, and insulation — and estimates your monthly running cost.
Run the BTU calculator
