With air conditioners, bigger is not always better. But the right size does matter and is always better. Especially when these appliances tap so much energy and resources, it’s crucial to get the correct size and model to meet your home energy needs. You’ll also want to keep operating costs, consumption, and impacts on the environment low.
Besides the AC unit size and model, the climate zone may also impact your purchase. For example, do you live in a hot climate? Or a humid climate? These are important questions to answer.
All of us have been newbies to HVAC installation at some point. A little guidance on the right sized air conditioner can go a long way, and you’ve found the right article to get started!
What Size AC Should you Get For a Small Room?
It’s always good to start small. Plus, not all homeowners want an air conditioner that pumps cold air through every single room of the house. Starting small is also a great way to keep costs down by air conditioning only a single room to start.
While it may seem OK to get a larger air conditioner (you can’t overdo coolness….right?) this can be a grave mistake.
Larger air conditioners with more BTUs will not only sap needly energy you’d be paying for. These models will also chill your space too fast and won’t process humidity nearly as efficiently. This can be pretty annoying in humid areas— think a very cold, clammy, and damp (not to mention frigid) room instead of something pleasantly cooler (and way less expensive).
So, for a Small Room, how do you Gauge the Right Size?
While smaller AC units are generally the right choice, look up the BTUs (short for British Thermal Units) on the product label of the air conditioner. The smallest air conditioners you can buy run at 5000 BTUs. So if you know your room space is tiny (anywhere under about 150 sq. ft.), it’s safe to say this is the right size for you. These air conditioners also tend to be very compact in size!
That said, is your room small but with great ceiling height? What about the number of windows and doors? This can increase the chance of passive heating. There are some additional calculations to consider if this is the case, which may call for a larger and higher BTU AC— but more on that later.
What Size AC Should you get for a Medium or Large Room?
As your room goes up in size by square footage, you’ll need to consider larger and larger AC units— and more and more BTUs to keep your space cool.
Smaller air conditioners with fewer BTUs are less ideal. They, too, will sap more energy and run less efficiently than is needed for a larger space, putting you more out of pocket for your energy consumption. (And the end product is a barely chilled room)!
What most would consider a medium-sized room is down to opinion, of course. But any room above 150 sq. ft. will need more than 5,000 BTUs to be cooled down by an air conditioner— and this number goes up by increments the more square footage you have.
For example, rooms between 150 square feet and 300 square feet will need 6,000 to 7,000 BTUs to cool down adequately and efficiently. 400 square feet will need 8,000 BTUs, 500 square feet will probably need 9,000 BTUs, and so on.
Really large rooms (up to 650 square feet and even more!) will need the most powerful air conditioning units you can buy, which tend to be about 12,500 BTUs. Now that’s some powerful cooling! Some can even chug along dynamically at 14,000 BTUs, depending on the model you buy.
I’m sure you’re starting to see a bit of a pattern here, and maybe you’re wondering: how is all this calculated?
Just read on to find out!
Air Conditioner Size Calculator
Small, large, medium— regardless of general size, is there an easy or fast-track way to figure out your space’s cooling needs?
Lucky for you, we’ve got a quick way to calculate that (which doesn’t depend on someone’s opinion of a “small” or “large” room).
It’s simple. For every square foot of space you need to cool, your AC unit will need roughly 20 to 25 BTUs. Measure the width and length of your room and then multiply it by 20 and 25 to get your ideal range of BTUs.
If you have high ceilings or other considerations, you can tweak this calculation a little. Large-windowed rooms (especially those with a high number of windows, south-facing rooms, and rooms that get a lot of sun illumination) and higher ceilings will need about 10% more BTUs. If the room is heavily shaded, you can drop the BTUs by 10%.
Some sources say more occupants or a kitchen area (that’s heated often by an oven and stove) will call for more BTUs. Add 600 more per person who regularly occupies the space and about 4,000 more for a kitchen space.
Can You Get an AC Unit to Cool Down the Entire House?
The answer is yes, and this will obviously call for the largest air conditioners with the most BTUs (in the 12,000 and 14,000 range) if your home is sizable. Small homes, apartments, and studio spaces could get away with less, though.
That said, a window unit won’t cool down an entire home, and you might need to look into installing a central air conditioner system. These are expensive up-front. But if you want an appliance that won’t break (or break the bank) and will keep your home comfortable, this is the best route to take and could actually cost you less with replacements in the long run.
Different Types of AC Units
AC units come in many sizes and types: window installation, wall installation, small, large— and there are portable ones so you can move from room to room on wheels! There is, of course, the central air type, the largest and most efficient (but also most pricey) of them all.
AC units are also not just defined by the type of BTUs but are also rated by the “ton,” or the tonnage/model number on their product labels (usually for outdoor AC units / central air conditioner). These also correlate to the BTU output or indicate how many square feet they can cool down.
Here’s a quick table:
- 18 model: 1.5 tons (for 600-1100 square feet)
- 24 model: 2 tons (for 900-1400 square feet)
- 30 model: 2.5 tons (for 1200-1650 square feet)
- 36 model: 3 tons (for 1500-2000 square feet)
- 42 model: 3.5 tons (for 1800-2300 square feet)
- 48 model: 4 tons (for 2100-2700 square feet)
- 60 model: 5 tons (for 2400-3300 square feet)
Keep in mind that the “ton” measurement isn’t the size or weight of the air conditioner unit; it’s a measurement of how much air a unit can cool down in an hour (1 ton is about 12,000 BTUs per hour). So getting the correct size AC unit for your house isn’t rocket science. With just a little education and the right calculation, you’ll have a beautifully comfortable summer space in no time!