Best Window Air Conditioner for a Large Room
Buy the TCL 12,000 BTU for a room of 450 to 550 sq ft, the TCL 14,000 BTU for 550 to 700 sq ft, or the Keystone 18,000 BTU for 700 to 1,000 sq ft. BTU is cooling power, so match it to your floor area. Running cost is $141 to $226 a year at 1,000 hours of use.
Our pick for each room size
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Check price on Amazon450 to 550 sq ft
TCL 12,000 BTU (T12WV9S)
12,000 BTU · CEER 16.0 · 115 V · about $141 a year to run · $489.99 on Amazon
Its CEER is higher than any 12,000 BTU unit in the table below, so it costs less to run than they do.
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Check price on Amazon550 to 700 sq ft
TCL 14,000 BTU (T14WV9S)
14,000 BTU · CEER 16.0 · 115 V · about $165 a year to run · $629.99 on Amazon
Its CEER is higher than any other 14,000 BTU unit on this page. It plugs into a regular 115-volt wall outlet.
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Want to spend less up front? The Keystone 14,000 BTU (KSTAW141WA) (CEER 15.0, 115 V) costs $549.99, $80 less than the TCL, and about $11 more a year to run.
Check price on Amazon -
Check price on Amazon700 to 1,000 sq ft
Keystone 18,000 BTU (KSTAW182WA)
18,000 BTU · CEER 15.0 · 230 V · about $226 a year to run · $656.99 on Amazon
It costs $42 less than the LG 18,000 BTU in the table below and has a higher CEER. It needs a 230-volt outlet (see the note below).
CEER is the efficiency rating; higher means a lower power bill. Amazon prices as of November 11, 2026.
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A room of 400 to 450 sq ft needs a 10,000 BTU unit. The TCL T10WV9S has the best CEER of the 10,000 BTU units below (16.0, 115 V) and costs about $118 a year to run, at $439.99.
Check price on Amazon
The 18,000 BTU units need a 230-volt outlet. The wall outlets in most rooms give 115 volts, and a 230-volt plug has a different shape and will not fit them. Check your wall before you order. If the room has no 230-volt outlet, an electrician has to add one. A 14,000 BTU unit uses the regular outlet, but it only cools up to 700 sq ft.
ENERGY STAR’s sizing chart: 450 to 550 sq ft needs 12,000 BTU, 550 to 700 sq ft needs 14,000 BTU, and 700 to 1,000 sq ft needs 18,000 BTU. For a room over 1,000 sq ft, use two units and add their BTU together. Add 10% of BTU for a very sunny room, 600 BTU for each regular user over two, and 4,000 BTU for a kitchen. The BTU calculator does the math.
Other 10,000 to 18,000 BTU window ACs you can buy today
Every unit here is certified by ENERGY STAR and has an Amazon listing we checked. Lowest price first. The 10,000 BTU units suit a room of 400 to 450 sq ft. Prices as of November 11, 2026.
| Unit | BTU | Room size | Volts | CEER | Per year | Price | |
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 Midea MAW10V1UWT | 10,000 | under 450 sq ft | 115 V | 15.0 | $126 | $399.99 | Check price |
| Keystone KSTAW101WA | 10,000 | under 450 sq ft | 115 V | 15.0 | $126 | $429.99 | Check price |
| TCL T10WV9S | 10,000 | under 450 sq ft | 115 V | 16.0 | $118 | $439.99 | Check price |
 Frigidaire Gallery GHWW105TE1 | 10,000 | under 450 sq ft | 115 V | 15.0 | $126 | $448.00 | Check price |
 BLACK+DECKER BD12NWES | 12,000 | under 550 sq ft | 115 V | 15.0 | $151 | $488.51 | Check price |
 LG LW1222IVSM | 12,000 | under 550 sq ft | 115 V | 15.0 | $151 | $519.00 | Check price |
 Hisense AW1422TW1W | 14,000 | under 700 sq ft | 115 V | 15.0 | $176 | $549.00 | Check price |
 Midea MAW14S1VWT-A | 14,000 | under 700 sq ft | 115 V | 15.0 | $176 | $564.99 | Check price |
 LG LW1822IVSM | 18,000 | under 1,000 sq ft | 230 V | 14.7 | $231 | $699.00 | Check price |
 Frigidaire FHWW145WE1 | 14,000 | under 700 sq ft | 115 V | 15.0 | $176 | — | Check price |
CEER is the combined efficiency rating; higher means a lower power bill. Running cost is 1,000 hours of cooling a year at 18.83 cents per kWh, the average U.S. residential rate (EIA), the same basis as the window AC vs mini split page. Room size is from ENERGY STAR’s chart for the unit’s BTU, and “under 550 sq ft” means the top of that size’s band. See every size of window AC or window ACs for a small bedroom.
Common questions
What size window air conditioner do I need for a large room?
Match the BTU to the floor area. ENERGY STAR’s sizing chart says 450 to 550 sq ft needs 12,000 BTU, 550 to 700 sq ft needs 14,000 BTU, and 700 to 1,000 sq ft needs 18,000 BTU, for an 8-foot ceiling.
Does a large window air conditioner need a special outlet?
The 18,000 BTU units do. They run on 230 volts, and a regular wall outlet gives 115. The 10,000, 12,000 and 14,000 BTU units in this list run on 115 volts.
How much does a large window air conditioner cost to run?
About $141 to $226 a year for the three picks, at 1,000 hours of cooling a year and 18.83 cents per kWh. Run it half as many hours and the cost halves.
Should I buy a bigger unit than the chart says?
Only for a reason the chart names. ENERGY STAR says to add 10 percent for a very sunny room, add 600 BTU for each person past two, and add 4,000 BTU for a kitchen. Otherwise stay with the chart size. For example, a very sunny 520 sq ft room needs 12,000 x 1.1 = 13,200 BTU, so buy the 14,000 BTU unit.
What if my room is over 1,000 sq ft?
Use two units and add their BTU together to reach the chart number. The chart calls for 21,000 BTU at 1,000 to 1,200 sq ft, 23,000 BTU at 1,200 to 1,400 sq ft and 24,000 BTU at 1,400 to 1,500 sq ft.
My room is between two sizes. Which one do I buy?
The chart bands touch at 550 and 700 sq ft, and a room of exactly 550 sq ft is a 14,000 BTU room, and exactly 700 sq ft is an 18,000 BTU room. Between two sizes, take the larger one if the room is sunny, has a kitchen, or holds more than two people, and the smaller one if not.
Room sizes and sizing tips are from the ENERGY STAR room air conditioner sizing chart. Efficiency ratings (CEER) and voltage are from the ENERGY STAR certified room air conditioner list. Running costs are our computation from those ratings. Amazon prices are what Amazon showed on the date under the picks. See methodology.