Portable Air Conditioner for Large Room

If you need a portable air conditioner for large room use, the best option is to buy the largest model available, which is 10,000 BTU.

And because we give our readers the facts, here’s one: You might not be able to effectively cool the room with a portable AC. Buying one could be a waste of money, and the reason why is explained here.

The largest unit, a 10,000 BTU portable air conditioner, is capable of cooling and dehumidifying rooms of 400 to 450 square feet, about the size of an average living room, large bedroom or home office.

What is the Largest Portable AC Size?

The largest portable air conditioner size is 10,000.

But portable ACs are sold that are labeled as 14,000 BTU. 

Here is an example from a popular online appliance retailer that sells Fridigaire, LG, GE, Danby and most other brands of portable AC:

Yes, it is confusing. The listing says it is a 14,000 BTU AC – meaning it will remove 14,000 BTUs of heat every hour.

But lower on the page, in the Specifications section, we find this clarification:

You can see that in the “fine print,” the DOE rating is given. 

But here is the problem – the “Cool Area” is given as 700 square feet, which is what you would expect from a room AC with an accurate BTU rating of 14,000 square feet – a window air conditioner or mini split air conditioner for example. 

But it is inaccurate to say that this unit can cool 700 square feet. The proper square footage is 400-450.

*We addressed this issue with the website, for the sake of consumers having accurate information to work with. It’s yet to be seen if the site will change the information on the page in question and all the others that give consumers misinformation.

Around 2020, the US Department of Energy revised its portable AC efficiency guidelines. The old ratings gave a false impression of a portable unit’s ability to remove heat from a home.

Portable Air Conditioners ASHRAE vs DOE Ratings

There’s a real difference when comparing ASHRAE vs DOE SACC ratings.

Yes, a 14,000 BTU unit could absorb and exhaust around 14,000 BTUs of heat per hour.

But, because of the way the units operate, two negative consequences occur while the unit is getting rid of heat.

1. Some of the heat transfers back into the room through the thin plastic exhaust hose prior to leaving the house.

2. More detrimentally, when air is pushed out of the room, warm and possibly humid air is pulled into the room. It’s either pulled from other rooms in the house, which might not be air conditioned, or from outside.

The result is that, roughly speaking, a 14,000 BTU unit absorbs 14,000 BTU of heat, but around 4,000 BTU of heat escape or are replaced when heat from outside is pulled into the room.

So, the net impact of running a 14,000 BTU portable air conditioner is the removal of approx. 10,000 BTUs of heat each hour.

That is why shoppers should not use the ASHRAE BTU rating to decide your portable AC size.  

The Bottom Line: 10,000 BTU is the largest portable AC using the updated ratings from the Department of Energy. And by the way, the new DOE BTU ratings do not apply to window air conditioners and mini splits since they do not have the same issues of leaking heat and pulling warm air into the room.

What is the SACC Rating?

SACC or seasonally adjusted cooling capacity is a technical term for the new DOE rating. You might see DOE or SACC or sometimes both used.

How Large is 400 Square Feet? 450 Square Feet?

These room sizes are common for this number of square feet:

• 20×20
• 18×22
• 16×25
• 15×27
• 20×22
• 18×25
• 16×28

What Size Portable AC for a Large Room?

The right size portable air conditioner for a large room is one with a DOE rating of at least 8,000 BTU. Depending on how efficient the AC is, 8,000 BTU DOE equals between 11,000 and 13,000 BTU for the old rating.

OK, now that the difference between DOE and ASHRAE ratings is understood, what’s the right size portable air conditioner for a living room? For a large bedroom or home office? First…

What is a large room for a portable AC?

Most homeowners consider anything above 300 square feet to be a large room. That’s 15×20, for example. Also about 16×18.

Portable Air Conditioner for a Large Room

Choose a portable AC with a rating of at least 7,500 up to one with a 10,000 BTU rating. Here’s a table showing the best size portable air conditioner for a large room based on the square feet in the room. Units with this range of capacity are designed for rooms from 300 to 450 square feet. That’s a room of about 15 x 20 to 15 x 30 or 20 x 23.

This Portable Air Conditioner Room Size chart shows you the best AC size for your room.

ASHRAE	DOE/SACC	PORTABLE AC SIZE
11,000	7,000 – 8,000	300 – 350 sq ft
12,000	7,000 – 1,0000	300 – 450 sq ft
13,000	8,000 – 10,000	350 – 450 sq ft
13,500	9,000 – 10,000	400 – 450 sq ft
14,000	9,000 – 12,000	400 – 550 sq ft
15,000	10,000 – 12,000	450 – 550 sq ft

Should I buy an Energy Star portable air conditioner?

NO. It isn’t possible. That would be a good idea, but portable units are not Energy Star certified. This is due to the inefficiency issues of losing heat before it is exhausted out of the house and also pulling warm air into the room. None of them are efficient enough to earn the Energy Star logo.

Factors that Affect Portable Air Conditioning

The chart above gives the bare minimum size of the correct portable AC for your purpose. You might need to buy a larger unit. And as stated at the start, you can’t go wrong buying the largest unit you can find. That isn’t true with any other type of AC including a window air conditioner. But because portable air conditioners aren’t that large to start with and they are so inefficient, you won’t over-cool a large room with the biggest you can find.

Here are factors to consider and how they affect your AC buying decisions.

First, start with the size needed based on the square footage of the room and the chart above. Then consider:

Ceiling Height: Rooms are 3-dimensional, so height has to be considered along with length and width. Most portable AC sizing charts are designed with 8-foot ceilings in mind. They might be OK for 9’ ceilings. But if your room has 10’ to 12’ ceilings, then step up to a larger size – get the biggest one available!

Does your room have a cathedral or vaulted ceiling? You might not be able to effectively cool it with one of these ACs. Yes, cool air sinks, so it stays nearer the floor, but with air movement, it will mix, and your AC will work extra hard to cool the space – if it can do it at all.

Room Location: Rooms with an outside wall facing west get very warm in the afternoon, so choose a larger unit for this room.

Floorplan: If the plan is closed, meaning you can close a door to the room, then you’re OK using the chart. But if the floorplan is open, and air flows in and out to adjoining rooms, then no portable AC is going to do the job. That’s the plain fact.

Home Construction & Condition: Newer homes and better insulated homes with tight envelopes (house wrap, no drafts around windows and doors) are easier to cool. If your home is older and draft, then get the biggest portable air conditioner available – yes, it can’t be said enough.

Number of people typically in the room: People make heat! A busy room like the living room needs more cooling energy than a bedroom where one person sleeps.

How to Make Your Portable Air Conditioner More Effective

Here are tips for getting the best air conditioning from your room air conditioner:

• Wrap insulation around the exhaust hose to prevent heat leak.
• Keep the door to the room closed as much as possible.
• If it’s an outside door, use weatherstripping to seal gaps that allow drafts.
• Put an insulated blind on each window to help prevent heat intrusion.
• Turn the unit on before the room gets warm enough that you feel like you need it cooled. For example, if the room typically gets too warm and needs AC in the late afternoon, turn on the air conditioner in the early afternoon, several hours before the room needs cooling.

Buy a DOE-rated 10,000 BTU AC for a large room! You won’t be sorry you did.

Alternatives to a Portable AC for Large Room Use

Portable air conditioners can be moved from room to room, and they aren’t heavy units that have to be lifted into and out of window openings. Those are great features. But if you decide that one of these room-to-room air conditioners isn’t going to work (one won’t work if the room is more than 500 square feet!), then you do have alternatives.

Window Air Conditioner

Window air conditioners for large rooms are manufactured with more than enough cooling power. Their ASHRAE ratings are accurate – if the package or information online says the unit is 15,000 BTU, that’s how much actual, effective cooling you’ll get. For a large room, consider a 10,000 to 20,000 BTU model based on your actual square footage to be cooled.

Another benefit is that when compared to a portable AC, window air conditioners are much more efficient. And some window ACs are Energy Star certified. Finally, the average cost of a window air conditioner for a large room is around $400 – $550. The average price of a large room portable AC is $475 to $700.

The main downside is the weight of a window unit makes it hard to lift into place and move from room to room.

Wall Air Conditioner

Compared to a window AC, a wall AC, aka through-the-wall AC, is more permanent and secure than a window unit. That’s an advantage and a disadvantage – it can’t be moved. And a hole for it has to be framed into an exterior wall of your home. The total cost of the unit and installation into the wall can easily exceed $1,000. 

Mini Split Air Conditioner

A ductless mini split AC or heat pump is your most efficient but most expensive choice for an air conditioner for a large room. You’ll spend more money on the system but save money every month on energy costs. The cost of a mini split AC for one room starts at about $1,500 for DIY equipment and $3,200 for those installed professionally. 

As a room AC, a mini split makes the most sense in warm to hot climates where the cooling season lasts from spring into fall or later. The unit will “pay for itself” over time as you save on energy costs. In cooler climates where AC isn’t so essential, a ductless AC won’t pay for itself. But the units are quieter, don’t take up window space or block the view, and they aren’t a security risk by leaving a window vulnerable to intrusion.