12000 BTU Window Air Conditioner Room Size

A 12000 BTU window air conditioner can cool a room of about 550 square feet under normal conditions – but there’s a longer answer that considers house and climate factors. We’ll give you all of the details on this page to allow you to answer the question based on your own circumstances.

What’s the Room Size for 12000 BTU Window AC?

A 12000 BTU window air conditioner can generally keep a 550 square feet room comfortable but there are several other factors to consider, including ceiling height that can affect the cooling ability of a window AC.

First we’ll give you the details on ceiling height. Below this Chart, you’ll find other factors that affect a 12000 BTU window air conditioner room size.

12000 BTU Air Conditioner Room Size by Ceiling Height

How high is your ceiling? It will affect how much space your AC can comfortably cool. 

12000 Btu Air Conditioner Room Size By Ceiling Height

Ceiling heightRoom size
6 feet640 sq ft
7 feet600 sq ft
8 feet550 sq ft
9 feet515 sq ft
10 feet475 sq ft

What size room for a 12000 BTU AC with 10 feet ceilings?

With 10 feet ceilings, a 12000 BTU AC can cool about 475 square feet because there is more cubic space than in a room with 8 feet ceilings. And although cool air will sink, causing the air around you to be slightly cooler than at the ceiling, having high ceilings will limit the effectiveness of the window air conditioner to cool the space.

Add a ceiling fan!  A ceiling fan can help whether you are heating or cooling the room. In the summer, the fan blades should be set to turn counterclockwise which will blow the air downwards to create a cool breeze. Reverse the rotation of the blades in the winter and the fan will pull cool air up and push warm air down.

What kind of room has 6 feet ceilings? Or 7 feet?

Typical ceiling height in most rooms is 8 feet but in upper floors in bungalows and in converted attic spaces, you find lower and sometimes, sloping ceilings with heights of 6 or 7 feet. A 12000 BTU AC can cool up to 640 square feet in rooms with 6 or 7 feet ceilings, if the room is well insulated.

12000 BTU AC Room Size by Outdoor and Indoor Temperature

Here’s another way to determine how much space a 12000 BTU window air conditioner can effectively keep cool.

If it’s very hot outside and you want the temperature very cool inside, then the smaller the space the AC can cool. For instance, when it’s 80F outside and you want to cool the bedroom to 77F, there’s only a 3 degree difference, so it won’t take a lot of air conditioning to cool the room.

But, if you like the bedroom at 72F and its 90F outside, that’s an 18 degree difference, so you will need more cooling capacity and a larger AC to cool a smaller room.

The following chart will visually explain this concept. In the middle column you’ll find Indoor Temperature choices. In the right column find Outdoor Temperature and note that the hotter it gets outside, the smaller the space the air conditioner can cool, which is shown in the Room Size column on the left.

Choose the Indoor Temperature that best fits your personal preference – 72F, 75F, and 78F.

The hotter it is outside, the harder your AC will have to work to keep the room cool – and it will affect how much space it can make comfortable. 

12000 Btu AC Room Size By Outdoor and Indoor Temperature

Room SizeIndoor TemperatureOutdoor Temperature
690 sq ft72 F82 F
580 sq ft72 F90 F
495 sq ft72 F95 F
470 sq ft72 F100 F
600 sq ft75 F90 F
550 sq ft75 F95 F
525 sq ft75 F100 F
625 sq ft78 F90 F
580 sq ft78 F95 F
540 sq ft78 F100 F

What room size for 12000 BTU AC when 90F outside?

If you want the room at 78F, which is 12 degrees cooler, a 12000 BTU air conditioner can cool up to 625 square feet. If you want the indoor temperature at 75F, then the AC can cool up to 600 square feet and if you want the room at 72F, the cooling capacity goes down to 580 square feet.

It is important to note that home insulation, number of windows the room has, how efficient they are, and whether it is a sunny or cloudy 90F will impact the cooling ability of a 12000 BTU AC.

Is the Room Size for a 12000 BTU Window AC the Same for a 12000 ASHRAE BTU Portable Air Conditioner?

No. A portable air conditioner has 2 BTU ratings. The older type of rating only indicates the maximum number of BTUs of heat the AC can move. These are referred to as the ASHRAE ratings which were developed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) and are the same as for a window air conditioner.

In 2017, the DOE ruled that ASHRAE ratings weren’t good enough for portable air conditioners because when a portable unit exhausts warm air from the room, it will always pull a little warm air back into the room. Plus, some heat transfers through the exhaust hose back into the space. Both issues make a portable AC less effective than a window unit of the same size.

So, the DOE (US Department of Energy) created a new system of ratings for portable ACs called the DOE SACC (Seasonally Adjusted Cooling Capacity) ratings.

The SACC ratings are generally 55% to 70% of the ASHRAE ratings.

This means that if you want 12000 BTUs of cooling from a portable AC, it’s best to use the DOE SACC rating to find one that will provide the 12000 BTUs of cooling power that you need.

Tip: If you prefer a portable AC and want the most effective type, choose a dual hose unit. They don’t pull as much hot air into the room as single-hose models do.

This Whynter dual hose portable air conditioner is an outstanding option.

Critical FAQs for 12000 BTU AC

Should I buy one large BTU AC and locate it in the middle of my apartment or 2 smaller, 6000 BTU units?

If climate control is your top priority, then buying two units will give you more balanced cooling and better dehumidification of humid air. Your cost will be higher, of course. But having two small units gives you versatility too, and they are not as heavy.

What is the minimum width for 12000 BTU window AC?

Without side panels, some 12K BTU window air conditioners can fit windows 20” wide. This GE is a good example.

What is the minimum window width for 12000 BTU window AC if installed with built-in panels?

With the side panels on, most window ACs need a window at least 22” wide. Many require 23”. But keep in mind that it is easy to remove those side panels. However, you’ll need to find another way to fill in the gap between the AC and window frame.

What is the minimum height for 12000 BTU window AC?

Most need the window to open at least 16”. But there are a few like this Midea U high-efficiency window AC that needs just 13 ¾” of opening.

How many amps does it take to start and run a 115v 12000 BTU air conditioner?

Depending on the efficiency of the unit, running amps range from about 8.7 to 10.0 for units currently being sold. Older ones might take up to 11.5 amps.

Starting amps are 2-3 times as high.

If they’re 115v ACs, you should be able to run them on a 20-amp circuit.

What’s the real difference between a 115v and a 230v 12000 BTU air conditioner?

Most units that are AC-only, no heating, are 115v air conditioners. When a heating element is added, then they are usually 230v air conditioners with supplemental heat like this one.

What size breaker for 12000 BTU air conditioner?

We would be safe and use a 20-amp breaker, though you might be able to use a 15-amp breaker if the circuit doesn’t have much else on it.

Written by

Rene has worked 10 years in the HVAC field and now is the Senior Comfort Specialist for PICKHVAC. He holds an HVAC associate degree from Lone Star College and EPA & R-410A Certifications.

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