How much does it cost to run a 18,000 BTU window air conditioner?

Data checked October 2026

Short answer

A 18,000 BTU window AC draws about 1.18 kW and costs $0.21 an hour running — about $161 over a 750-hour U.S.-average cooling year at 18.19¢/kWh.

Power = capacity ÷ efficiency: 18,000 BTU/h ÷ CEER 15.23 = 1,182 W.
DOE rates room air conditioners on 750 full-load hours a year; spread by U.S. cooling degree days that peaks in July at about 6.4 hours a day — $42.56 that month.
Window units made since May 26, 2026 must meet CEER 16, so a new unit of this size draws at most 1,125 W.
In a hot state the same unit runs far more: Texas has 2.2× the U.S. cooling degree days, Florida 2.8×. Pick your state in the calculator.

Adjust it to your exact job

Your air conditioner

Type

Size

Efficiency

How much it runs

Run time

750 full-load hours a year: DOE's 750-hour national basis × 1,216 cooling degree days in the U.S. ÷ 1,216 U.S.

Electricity rate

Where you live

Price per kWh

EIA's state average: total residential revenue ÷ kWh sold, so delivery and fixed monthly charges are spread over every kWh.

18,000 BTU window AC in July

$42.56a month

$161 a year (886 kWh) · $0.21 per hour running

At 18.19¢/kWh — U.S. average, Jan–Aug 2026 (EIA).

Per hour running: $0.211.18 kW average draw
Busiest month (Jul): 6.4 hfull-load hours a day
Per year: $161750 full-load hours
Capacity: 18,000BTU/hCEER 15.23

Estimated monthly cost in the U.S.

Same use, other efficiency

Yearly cost by efficiency rating
Efficiency	Per year	vs yours
ENERGY STAR average (CEER 15.23)	$161	—
2026 federal minimum (CEER 16)	$153	−$7.76

New units beat this average

Window units of this size made since May 26, 2026 must reach CEER 16; the ENERGY STAR list still includes older models averaging 15.23.

How to cut it

Raise the thermostat a few degrees and run a ceiling fan instead — an ENERGY STAR fan uses about 35 W on high.
Change the filter and keep the outdoor coil clear of leaves and grass so the system moves heat as rated.
Close blinds on sun-facing windows in the afternoon, when cooling hours peak.
Pick the size for the room: an oversized window unit cycles on and off and leaves the air clammy.

Energy budget

886 kWh 18,000 BTU window AC — cooling season electricity750 full-load hours at 18.19¢/kWh$161

Estimated total$161

Did this answer your question?

Compare

Every size at 18.19¢/kWh and 750 full-load hours a year

Size	Efficiency	Watts	Per hour	Per year
5,000 BTU	CEER 14.07	355	$0.06	$48.48
6,000 BTU	CEER 14.21	422	$0.08	$57.60
8,000 BTU	CEER 15.23	525	$0.10	$71.66
10,000 BTU	CEER 15.35	651	$0.12	$88.88
12,000 BTU	CEER 15.2	789	$0.14	$108
14,000 BTU	CEER 15.47	905	$0.16	$123
18,000 BTU	CEER 15.23	1,182	$0.21	$161
24,000 BTU	CEER 13.35	1,798	$0.33	$245

How this was worked out

18,000 BTU/h ÷ 15.23 = 1,182 W = 1.182 kW. × 18.19¢ = $0.21 per running hour. × 750 hours = $161 a year.

Prices are EIA's U.S. average residential price for Jan–Aug 2026. Efficiency figures are ENERGY STAR certified averages (window units) or the federal minimum shown.

The full method, material data and tips are on the main air conditioner cost calculator page.

Similar jobs

Other sizes people check

Sources

Data behind this answer

EIA Electric Power Monthly, Tables 5.6.A & 5.6.B — residential price by state (August 2026) — latest month and Jan–Aug 2026 year-to-date average for every state; preliminary, refreshed monthly · checked October 2026
ENERGY STAR certified room air conditioners (dataset) — average CEER by size for window units; 750 hours/yr label basis · checked October 2026
ENERGY STAR certified central AC & heat pumps (dataset) — 3-ton split average SEER2 17.06 / EER2 11.49 / HSPF2 8.44; 12k mini-split SEER2 22.81 · checked October 2026
10 CFR 430.32 — federal energy conservation standards (eCFR) — room AC CEER minimums from 2026-05-26; SEER2 regions; dehumidifier IEF; water heater UEF · checked October 2026
NOAA Climate Prediction Center — population-weighted state degree days — monthly normal heating and cooling degree days by state (base 65°F) · checked October 2026
EIA-861M sales and revenue by state — 2025 average household use and bill per state (U.S. 878 kWh, $151.88 a month) · checked October 2026
EIA Electric Power Monthly technical notes — average price = revenue ÷ sales, including fixed customer charges, fuel adjustments and surcharges · checked October 2026

Short answer

A 18,000 BTU window AC draws about 1.18 kW and costs $0.21 an hour running — about $161 over a 750-hour U.S.-average cooling year at 18.19¢/kWh.

Power = capacity ÷ efficiency: 18,000 BTU/h ÷ CEER 15.23 = 1,182 W.

DOE rates room air conditioners on 750 full-load hours a year; spread by U.S. cooling degree days that peaks in July at about 6.4 hours a day — $42.56 that month.

Window units made since May 26, 2026 must meet CEER 16, so a new unit of this size draws at most 1,125 W.

In a hot state the same unit runs far more: Texas has 2.2× the U.S. cooling degree days, Florida 2.8×. Pick your state in the calculator.

Adjust it to your exact job

Your air conditioner

Type

Size

Efficiency

How much it runs

Run time

750 full-load hours a year: DOE's 750-hour national basis × 1,216 cooling degree days in the U.S. ÷ 1,216 U.S.

Electricity rate

Where you live

Price per kWh

EIA's state average: total residential revenue ÷ kWh sold, so delivery and fixed monthly charges are spread over every kWh.

18,000 BTU window AC in July

$42.56a month

$161 a year (886 kWh) · $0.21 per hour running

At 18.19¢/kWh — U.S. average, Jan–Aug 2026 (EIA).

Per hour running: $0.211.18 kW average draw
Busiest month (Jul): 6.4 hfull-load hours a day
Per year: $161750 full-load hours
Capacity: 18,000BTU/hCEER 15.23

Estimated monthly cost in the U.S.

Same use, other efficiency

Yearly cost by efficiency rating
Efficiency	Per year	vs yours
ENERGY STAR average (CEER 15.23)	$161	—
2026 federal minimum (CEER 16)	$153	−$7.76

New units beat this average

Window units of this size made since May 26, 2026 must reach CEER 16; the ENERGY STAR list still includes older models averaging 15.23.

How to cut it

Raise the thermostat a few degrees and run a ceiling fan instead — an ENERGY STAR fan uses about 35 W on high.
Change the filter and keep the outdoor coil clear of leaves and grass so the system moves heat as rated.
Close blinds on sun-facing windows in the afternoon, when cooling hours peak.
Pick the size for the room: an oversized window unit cycles on and off and leaves the air clammy.

Energy budget

886 kWh 18,000 BTU window AC — cooling season electricity750 full-load hours at 18.19¢/kWh$161

Estimated total$161

Size

Efficiency

Watts

Per hour

Per year

5,000 BTU

CEER 14.07

355

$0.06

$48.48

6,000 BTU

CEER 14.21

422

$0.08

$57.60

8,000 BTU

CEER 15.23

525

$0.10

$71.66

10,000 BTU

CEER 15.35

651

$0.12

$88.88

12,000 BTU

CEER 15.2

789

$0.14

$108

14,000 BTU

CEER 15.47

905

$0.16

$123

18,000 BTU

CEER 15.23

1,182

$0.21

$161

24,000 BTU

CEER 13.35

1,798

$0.33

$245

How this was worked out

18,000 BTU/h ÷ 15.23 = 1,182 W = 1.182 kW. × 18.19¢ = $0.21 per running hour. × 750 hours = $161 a year.

Prices are EIA's U.S. average residential price for Jan–Aug 2026. Efficiency figures are ENERGY STAR certified averages (window units) or the federal minimum shown.

The full method, material data and tips are on the main air conditioner cost calculator page.