How to Choose the Right BTUs for a Portable Air Conditioner?

Portable air conditioners shouldn’t be approached with a “bigger is better” attitude, or even a “well, this one was on sale so I bought it” approach. This guide will show you how to size a portable AC in terms of BTUs, a specification that all of today's units carry on their labels.

What Is a BTU?

Portable air conditioners are rated in British Thermal Units (BTUs) per hour. There are other features and characteristics to consider when making your final choice, but nothing is more important than selecting a unit with the right BTUs for your room, environment and needs.

BTU is an acronym that stands for “British Thermal Unit”. It is a measurement of how much energy is required to raise the temperature of one pound of water by one degree. Any portable air conditioner you come across will have its BTU amount displayed prominently.

Generally, models with higher BTU ratings can offer more cooling power and can cover larger rooms.


Too Many or Too Little Is BAD

It's important to buy a portable AC that's appropriate for your space to make sure you don't waste energy or waste your money on one that can't adequately cool your room.

If you use a portable A/C with too a high BTU rating in a small room, you’ll experience unsatisfactory results, while also decreasing the lifespan of your air conditioner. The unit will cool very quickly, but then cycle off and then back on. The repeated cycling will cause the unit to not remove the humidity from the air like it’s supposed to.The end result is an overworked air conditioner, an energy bill that is higher than it should be, and a room that feels balmy from the excessive humidity generated.

An insufficient amount of BTUs is just as bad. If your room is too big for your unit’s BTU rating, it will run its cycle non-stop and overwork the air conditioner. You’re left with a hot room and a higher energy bill, and wasted money on a unit that can’t do its job.

Calculate How Many BTU’s You Need

For ordinary homeowners, BTUs are difficult to estimate precisely, but you can still select the right unit with the right range of BTUs to match your cooling needs and leave you with a properly cooled room.

Figure out the room size in square feet of the room you would like to keep cool. Simply multiply the length of the room by the width, and you have your square footage.

In a standard room with 8-foot ceilings, use these estimations:


 Note: The guidelines above are not exact. Environmental factors may increase or decrease the number of BTUs required. If you have any questions about what size you should buy, feel free to email us at before your purchase.

Thank you.