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How Much to Run a Window AC in Illinois? $0.21/Hr, $57/Summer

Running window air conditioner in Illinois costs about $0.21 an hour and roughly $57 for the summer — 1,100 W for 2.9 hours a day at 19.22¢/kWh.

$0.21per hour
$57per summer, 92 days
778cooling degree-days, NOAA

· Source: EIA Electric Power Monthly Table 5.6.A (July 2026 data) · next EIA update ~Oct 23

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Window air conditioner in Illinois: watts ÷ 1,000 × hours × days × rate. Estimate, not a quote.
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Per hour
$0.21 at 19.22¢/kWh
Per summer
$57 (92 days)
Hours per day
2.9 (NOAA state cooling degree-days-scaled)
Degree-days used
778 (NOAA CPC state, population-weighted)
Wattage
1,100 W (typical 500–1,500)
Illinois rate
19.22¢ (July 2026)
Rank of 20 cold states
3 (3rd most expensive)

Why this number

Running window air conditioner in Illinois costs about $0.21 an hour and roughly $57 for the summer — a 1,100 W unit for 2.9 hours a day over 92 days (June–August) at Illinois’s July 2026 average of 19.22¢/kWh. The hours are the national 3.6 h/day baseline scaled by NOAA CPC state population-weighted CDD, June–August 2026 (778 vs the CONUS 958); your utility’s rate moves it (table below), and the calculator takes your own wattage, hours and rate.

Illinois runs window air conditioner less than the national baseline in June–August — 2.9 hours a day on the NOAA state degree-day scaling used here, against 3.6 nationally — and pays 19.22¢/kWh for it. Those two numbers, times 1,100 W, are the whole $57.

Window air conditioner cost in Illinois by hours per day — per day / per summer

Window air conditioner cost per day and per summer in Illinois at 1 to 12 hours a day, at the state average rate and its largest utilities' EIA-861 prices
Hours per day Illinois avg 19.22¢ Commonwealth Edison Co 13.4¢ Ameren Illinois Compan 11.8¢ MC Squared Energy Serv 6.8¢
1 h $0.21 / $19 $0.15 / $14 $0.13 / $12 $0.07 / $7
2 h $0.42 / $39 $0.29 / $27 $0.26 / $24 $0.15 / $14
4 h $0.85 / $78 $0.59 / $54 $0.52 / $48 $0.30 / $28
6 h $1.27 / $117 $0.88 / $81 $0.78 / $72 $0.45 / $41
8 h $1.69 / $156 $1.18 / $108 $1.04 / $96 $0.60 / $55
12 h $2.54 / $233 $1.77 / $163 $1.56 / $143 $0.90 / $83

What Illinois’s utilities charge for it

Illinois's largest electric utilities and what window air conditioner costs per hour and per summer at each one's average price
Utility Residential customers ¢/kWh (EIA-861 2024) Per hour Per summer at 2.9 h/day
Commonwealth Edison Co 3,727,675 13.4¢ $0.15 $40
Ameren Illinois Company 1,060,894 11.8¢ $0.13 $35
MC Squared Energy Services, LLC 244,008 6.8¢ $0.07 $20

What the numbers say about window air conditioner in Illinois

Illinois logged 778 population-weighted cooling degree-days over June–August (NOAA CPC state series), 81% of the CONUS figure of 958, which is why this page runs window air conditioner 2.9 hours a day against the national 3.6 — 0.7 hours less. At Illinois’s July 2026 rate of 19.22¢/kWh that makes it the 3rd most expensive of the 20 cold states for window air conditioner: $57 for the 92-day summer, against Montana’s $14 and Alaska’s $68. Commonwealth Edison Co, Illinois’s largest utility with 3,727,675 residential customers, averages 13.4¢ — $40 for the same hours — while MC Squared Energy Services, LLC at 6.8¢ comes to $20, a $20 spread on identical use. Illinois’s July 2026 rate of 19.22¢ sets the $0.21 per hour; its winter average of 17.86¢ is 1.36¢ lower, a difference that matters for heating loads but not for window air conditioner use in June–August.

Frequently asked questions

How much does it cost to run window air conditioner per hour in Illinois?

$0.21 an hour for a 1,100 W unit at Illinois’s July 2026 average of 19.22¢/kWh (1,100 ÷ 1,000 × 0.1922); at Commonwealth Edison Co’s 13.4¢ it is $0.15.

How much does window air conditioner cost for the whole summer in Illinois?

About $57: 1,100 W × 2.9 hours a day × 92 days (June–August) × 19.22¢. The hours are the national 3.6 h/day scaled by NOAA CPC state population-weighted CDD, June–August 2026 (778 against the CONUS 958); enter your own hours above for your own figure.

Is window air conditioner expensive to run in Illinois compared with other cold states?

Illinois is the 3rd most expensive of the 20 cold states on this site at $57 a summer; the range runs from Montana ($14) to Alaska ($68), driven almost entirely by the electricity rate.

How we calculated this

Worked for window air conditioner in Illinois: 1,100 W ÷ 1,000 × 0.1922 $/kWh = $0.21 per hour; hours per day = 3.6 × (778 ÷ 958) = 2.9; 1,100 ÷ 1,000 × 2.9 × 92 × 0.1922 = $57 for the summer. Rate: EIA Electric Power Monthly 5.6.A (July 2026); degree-days: NOAA CPC state population-weighted CDD, June–August 2026, against the CONUS total; utility prices: EIA-861 2024.

Sources: U.S. Energy Information Administration (EIA) electricity rates · DSIRE incentive records · public IRS/OBBBA guidance. Figures are modeled estimates, not quotes or tax advice. See our methodology.

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