8000 BTU Window Air Conditioner Room Size

What size room for 8000 BTU window air conditioner?

The short answer is that an 8000 BTU window air conditioner can cool a room of up to 350 square feet under typical cooling conditions.

But there are other factors that mean an 8000 BTU AC will cool more or less space.

This page will give you all of the details allowing you to answer the question based on the specific details of our room.

What’s the Room Size for 8000 BTU Window AC?

Depending on the height of your ceilings, an 8000 BTU window air conditioner is designed to keep a 350 square foot room comfortably cool.

Here are the details about the ceiling height and cooling effectiveness. Below this Chart, we cover other factors that will affect an 8000 BTU window air conditioner room size.

8000 Btu Air Conditioner Room Size By Ceiling Height

Ceiling height Room size
6 feet 465 sq ft
7 feet 400 sq ft
8 feet 350 sq ft
9 feet 310 sq ft
10 feet 280 sq ft

What size room for an 8000 BTU AC with 10 feet ceilings?

The answer is about 280 square feet. A room with a tall ceiling has more volume than a room with standard ceilings, so there are more cubic feet to cool. Since cool air does sink, the air in the mid to lower areas of the room will be a little cooler, but having 10 foot ceilings will reduce the ability of the AC to cool the entire space.

Tip: You can install a ceiling fan for high ceilings! A ceiling fan will help with cooling and heating a room. Set the fan so the blades turn counterclockwise in the summer to create a breeze. In the winter, set the blades to turn in a clockwise direction which will pull cool air up and away from you, and push warm air down to where you are.

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

8 feet ceilings are the standard size for most rooms. Rooms with lower ceilings include upper floors in bungalows and converted attic spaces where you find lower or sloping ceilings due to the roof. An 8000 BTU AC can cool up to 465 square feet in a room with 6 or 7 feet, if the room is well insulated.

8000 BTU AC Room Size by Ambient and Indoor Temperature

You can also look at how much space an 8000 BTU window air conditioner can cool by air temperature.

If the outside temperature is very high, and you want the temperature inside very cool, then the less square footage the AC can cool. In other words, the greater the difference between the outside and desired inside temperatures, the less space the air conditioner can cool.

For instance, if it’s 80F outside and you want to cool your bedroom to 75F, there’s only a 5 degree difference in temperature which won’t take a lot of air conditioning. But, if it’s 90F outside and you would like the bedroom at 72 degrees, that’s a difference of 18 degrees which will take much more cooling power. Depending on the size of your bedroom, you may need an AC with higher BTUs to keep the room cool.

The chart below is a visual guide explaining this point. Use the Indoor Temperature in the middle column to find the temperature you would like. Now look at the right column, Outdoor Temperature, and note that the hotter it gets outside, the smaller the room size the AC can cool – see the Room Size column on the left.

We list three Indoor Temperatures so you can find one that fits your personal preferences, 72F, 75F, and 78F.

8000 Btu AC Room Size By Outdoor and Indoor Temperature:

Room Size Indoor Temperature Outdoor Temperature
600 sq ft 72 F 82 F
390 sq ft 72 F 90 F
300 sq ft 72 F 95 F
250 sq ft 72 F 100 F
465 sq ft 75 F 90 F
350 sq ft 75 F 95 F
280 sq ft 75 F 100 F
550 sq ft 78 F 90 F
410 sq ft 78 F 95 F
320sq ft 78 F 100 F

This table is based on an 8 feet ceiling height with average insulation. 

What room size for 8000 BTU AC when 90F outside?

If you want the temperature inside 12 degrees cooler, at 78F, the air conditioner will cool up to 550 square feet. If you want it cooler inside, say 75F, the room size drops to 465 square feet. If you want the room 18 degrees cooler, which would be 72F, the cooling capacity goes down to 390 square feet.

Keep in mind that how well your home is insulated, the number of windows in the room and how efficient they are, plus whether it’s a sunny or cloudy 90F outside, all affect how well an 8000 BTU AC will cool.

Is Room Size of an 8000 BTU Window AC the Same for an 8000 ASHRAE BTU Portable Air Conditioner?

Not quite. Portable ACs now have two BTU ratings. The older one is based only on the maximum number of BTUs of heat the air conditioner can move. That’s the same as a window air conditioner, and these ratings are referred to as ASHRAE ratings which were developed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE).

But, in 2017, the DOE (Department of Energy) said that is not really accurate. When a portable air conditioning unit exhausts warm air from the room, it will always pull some warm air back into the room, so it doesn’t run as effectively as a window air conditioner.

The DOE came up with a new rating system for portable ACs called the DOE SACC (Seasonally Adjusted Cooling Capacity) ratings. The SACC ratings are lower than the ASHRAE ratings.

The SACC ratings are a little more than half the ASHRAE ratings.

So, if you want 8000 BTUs of cooling power from a portable AC, use the DOE rating, instead of the ASHRAE rating, to find one that actually does deliver 8000 of AC power.

Here’s our Guide to the DOE SACC vs ASHRAE BTU Ratings. 

Critical FAQs for 8000 BTU AC

What is the minimum width for 8000 BTU window AC?

The minimum width for standard window air conditioners is about 19 inches, but there are just a few this narrow. For most window ACs, the minimum window width is 22 inches (22”).

Here are two of the best 8000 BTU window air conditioners available today for narrow windows.

The Gree 8000 BTU with 3 modes and remote control is perfect for narrow windows that open up and close down, rather than opening side to side. It is just 18.6 inches wide, the narrowest standard window AC around.

This GE 8,000 BTU window AC with WiFi also needs a window about 19” wide. The actual width is 18.56”. Like the Gree model, it is highly rated.

For both models, you’ll probably need to remove the wings to fit into a window that narrow. With the wings on, the window will have to be 22” minimum.

What is the minimum height for 8000 BTU window AC?

About 14” for most. Be sure, though, by measuring the window opening from the top of the sill to the bottom of the part, the sash, that opens. And then shop for window air conditioners that will fit into that gap.

The Gree and GE window ACs just mentioned fit 13” windows, but we use the 14” measurement just to be sure.

How many starting and running watts is an 8000 BTU AC?

An 8000 BTU window air conditioner requires around 1200 watts to start and between 650 and 800 watts to run. The GE window AC above runs on 695 watts and requires around 1100 to start.

What size breaker do you need for an 8000 BTU AC? If there is little else on the circuit, then a 15-amp breaker will be fine.

Can you plug an 8000 BTU air conditioner into a power strip?

Yes, you can, but with two conditions.

First, the power strip must be newer and in good condition.

Secondly, the power strip must be rated for at least 15 amps, like this one.

And don’t load up the power strip with a lot of high-wattage devices like a space heater or hair dryer, and you should be OK.

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 and EPA & R-410A Certifications.

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