How to Find the BTU on an Air Conditioner

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Updated May 18, 2023

Knowing how to find out the BTU on an air conditioner is essential when determining a suitable model for your house or room. Even the best air conditioner in its class won’t be effective if its BTU rating is too low. Thankfully, easy to figure out any air conditioner’s rating by checking the information on your AC unit. However, if it’s not there, keep reading to learn of other ways to locate the BTU rating.


  • You can usually find an AC unit’s BTU rating displayed on its side, along with information like safety warnings.
  • Retailers and manufacturers also list BTU ratings for the models they sell on their websites.
  • The BTU rating indicates the size of the room a model is best suited to cooling.

While you’re at it, ‌read about how to install a portable air conditioner if that’s the kind you’ve chosen. You may also want to look into how to find an AC leak in a central air conditioner. If you’re still shopping for units,m you’ll want to know how many watts does a portable A/C use and for tech-savvy folks, you’ll want to know how to control an A/C from a mobile phone.

Locating the BTU Rating on an Air Conditioner

BTU stands for British Thermal Unit, which measures an AC unit’s cooling power. One BTU equals the amount of energy required to increase the temperature of 16oz of water by 1°F. This water will collect as the unit works, so remember to drain the water from your window A/C. Additionally, to keep up with maintenance, remember to defrost frozen AC pipes once in a while.

Insider Tip

The BTU rating of an AC unit is often found on its side.

The BTU rating of an AC unit roughly indicates the square footage that a unit can cool at maximum effectiveness and efficiency. A 5,000 BTU unit, for example, is ideal for a 150-250 square foot room, while an 18,000 BTU unit is meant for huge spaces of 600-900 square feet. A 12,000 BTU unit like the one in this Avallon dual hose portable air conditioner review can handle cooling 450 square ft. Once you’ve measured your area and determined the BTU rating you need, you can select a model with the cooling power to do the job.

Finding the BTU Rating

Finding the BTU rating of an AC unit is easy. The first place to look is on the unit itself. Usually, the BTU rating is displayed on one side of a window unit with the model number and other essential information, like serial numbers and safety warnings. On other unit types, you should still be able to find it without too much trouble.

If you can’t find the BTU on the unit itself, it should be listed online in the unit’s product description. You may have to call the manufacturer with your model number if it isn’t. However, nine times out of 10, a unit’s BTU rating will be displayed on the model itself, so it’ll be a rare occurrence you’ll have to take any further steps. This way, you’ll know how well the unit will cool your space, like how the best 12000 BTU air conditioner would be a great fit for a small apartment.


To avoid high energy costs and ensure maximum cooling efficiency, avoid using an AC unit with a BTU rating too low for your space.


What size air conditioner do I need?

The size you need depends on the size of the space. A BTU rating will tell you what size room a unit can cool. The lowest common BTU rating is 5,000 BTUs, and models with this rating are best for 150-250 square feet spaces. The highest rating is 18,000 BTU, which can cool an area of around 600-900 square feet.

What happens if you don’t have enough BTUs?

Using an air conditioner in a room with a lower BTU rating than is recommended will have a couple of effects. First, it won’t cool the room as effectively, taking longer to reach the desired temperature or possibly not being able to reach it at all. Second, it’ll be far less efficient, increasing energy costs and shortening the unit’s lifespan.

What does BTU mean in air conditioners?

BTU is an acronym for British Thermal Units, which is the universal standard for rating the cooling power of an air conditioning unit. Specifically, a BTU is the amount of energy required to raise or lower the temperature of 16 oz of water by 1 degree Fahrenheit.

STAT: The average size of a studio apartment in the U.S. is about 500 square feet. An 8-10,00 BTU air conditioner would cool it efficiently. (source)

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