Is the Size of Room I’m Putting My Air Purifier in Important?


One of the most important factors in finding an air purifier is the size of room it is meant to service. You can’t put an air purifier that’s built for 100 square feet in a room that’s 500 square feet and expect the same level of clean air. As such, the size of air purifier that you buy is of the utmost importance.

Because of this, a lot of air purifier companies will build air purifiers that are very similar, but built for different sized rooms. The Blueair Blue Pure series, for example, has tiers for rooms that are small, medium, large, and extra-large. All of these air purifiers work the same way, but they are different sizes and are built for different sized rooms.

Sure, you can put one of the air purifiers for smaller rooms into a larger room, but the overall cleanliness of the air, and the ability for the air purifier to cycle all the room’s air through it, will suffer. On the other hand, you can put an air purifier that’s built for larger rooms and put it in a smaller room, but that’ll be a bit overkill. But maybe you like overkill and want extra clean air, that’s your call though.

Now to put this air purifier size question into slightly more accessible terms, let me use a metaphor.

Air Purifiers Are Like Paint Brushes

Your air purifier is like a paint brush.

Are you going to paint the walls in your home with a tiny paint brush, or are you going to use a big one (or use a paint roller, maybe)?

You’re going to use a bigger brush because it’ll get the job done dozens of hours faster, and it’ll do a better job.

Conversely, are you going to paint a picture with the same big old brush? No! You’ll use a smaller one.

Each paint brush serves a purpose and there are ones that are made for smaller detail work and others for larger work that just needs filled in.

Air purifiers are just like this. There are ones for big areas and ones for small ones. You can try to put a small one in a big room or a big one in a small room, but you’ll see the best result for your dollar by putting the right one in the right size of room.

How Do I Calculate the Size of My Room?

If you don’t know the size of your room, then you can easily find out. Grab a tape measure (or a ruler) and measure out the width and length of your room.

Yes, all that high school geometry class work is coming back to haunt you right now.

You might need to use your phone’s calculator app, or just grab a normal calculator to then multiply the width and length.

So, for an easy example, here’s a diagram of a room for you. As you can see, the width is 15 and the length is 10. Multiply those together, and you’ve got 150 square feet. (Note, when you multiply the length and width, you get “square feet” rather than just normal feet. There’s reasons for that, but I won’t bore you with that today.)

Okay, I’m sure someone is now thinking something like “NO! Wait! My room isn’t a perfect rectangle like that!” Or, you might be thinking about the adjoining/connected rooms in your house.

Don’t worry, funky shaped rooms and adjoining rooms just mean you need to do a tiny bit of addition. Just take the length and width of all those different rectangles and add them together. Here’s another diagram to help you figure this out…

Alright, there’s a messy bunch of rooms!

Now, I made a mess of rooms like this to really prove my point that this is easy, but I have to say right now that this particular scenario will only work if these three rooms are all adjoining/connected and do not have doors separating them. Air purifiers can’t clean air through a door.

But, if these rooms are truly attached, then you’re clear to run your numbers!

Top Left Room:

20 times 8 is 160

Bottom Room:

25 times 10 is 250

Top Right Room (A Hallway)

4 times 10 is 40

Now all we have to do is add up those three rooms. I made each room’s square footage bold so it’s easier to spot.

160 plus 250 plus 40

That’s 450 square feet.

So, if you were buying an air purifier for these three adjoining rooms, then you’ll want to buy an air purifier that’s made for rooms that are 450 square feet.

What if I Can’t Find an Air Purifier for a Room That’s the Same Square Feet as Mine?

Odds are that you won’t find many air purifiers that are made for exactly the same size room as the one you’re going to put it in. That’s how the real world works, most of the time.

If you can’t find an air purifier that’s rated for the exact size that your room is, then you can fudge your numbers a bit. Try to get an air purifier that most closely matches your room’s size and try to error on getting one that’s made for a little bigger of a room rather than one that’s smaller just to be sure that you’re getting the best possible air quality.

Now, I get it, that’s all fine and dandy, but what exactly does it me?

Let’s continue off our second example.

So, your room is 450 square feet. There aren’t many air purifiers out there made for that size.

But there are some that are made for 400 square feet, and others made for 500.

Following my rule, I would personally get the 500 square foot air purifier. But, you don’t’ have to do that if you don’t want to. You can get an air purifier for 400 instead. Full disclosure, your air quality might suffer a bit, but odds are you won’t be able to notice too badly. That being said, if you have bad allergies or asthma, go for the bigger one.

If I didn’t scare you with that, then here’s another choice for you, you can buy multiple smaller air purifiers to service the same combined area. So, for the second example, that means you’d probably buy an air purifier for the 40 square foot hallway, one for the 250 square foot lower room, and a third for the 160 square foot top left room.

I know, choices, choices.

At the end of the day, you can literally do whatever you want. You can buy a hundred air purifiers, you can buy the best air purifier on the market, the worst one, one for a tiny room, one for a huge one, you might even not buy one. Whatever you opt to do, I just hope I was able to inform you on the importance of getting one that’s made for the room you’re putting it in (give or take a few square feet).

Now, if you’re ready to pick up an air purifier, might I recommend another one of my articles where I recommend various systems that have really won me over?

EnviroKlenz UV-C Air Purifier Unboxing and Setup

Top Five Affordable Air Purifier Dehumidifier Combination Units | What is the Best Air Purifier I Can Buy?

My Favorite Air Purifier | Blueair 211+ Air Purifier | What is the Best Blueair Air Purifier for My Home?

Is Where I Put My Air Purifier Important?

Alright, we’ve addressed the need for getting an air purifier that’s actually made for the size of room you’re putting it in, but that now leaves us a few other questions. For one, that’s what you should look for in an air purifier. Another is how can you buy one. I’ve got an article for both, which I’ve already written, so I’ll let you check those out, if you’re interested in them.

But something I haven’t addressed is where you should put your air purifier.

After all, there’s a lot of potential spots in your room(s). Lots of hiding places, lots of spots in the middle of the room. A few nice corners to tuck it away. Where’s the best place to put an air purifier?

Well, the best place to put an air purifier is somewhere that allows it to both pull in air, and somewhere that’s not too tucked away. You want to allow your air purifier to have plenty of room, maybe a foot or so, on whatever side it has its intake and output vents in order for the air to circulate. You also want to have your air purifier along the edge of your room and not in a corner, if at all possible.

The reasoning behind allowing your air purifier room to breathe is pretty obvious, so I’ll leave it at that. What is less obvious is the reason to not put it in a corner.

Let me enlighten you.

While corners might seem appealing, they’re not the best possible place for your air purifier because the air purifier’s air flow might not be able to reach the corner opposite of the one it is in as well as it could if it were more centrally located.

Think of it this way, if you are blowing bubbles with your kid, are you going to blow them into a corner, or are you going to blow them out in the open where they will be able to float around freely?

This is an effective (if a bit simplistic) idea of what you want to do with your air purifier. Allow it to blow out into the most open area possible in order to help it clean the most air possible in your room.

Additionally, don’t bury it under clutter, that won’t let it breathe.

Now, I’m sure you’re all wondering where you can put an air purifier now, so I’m going to provide a few shots of places where you can put your air purifier in a few different rooms (including the second example I keep referencing above).

As you can see here, in these adjoining rooms, you’ll probably want to put the air purifier where the big green star is on the right side.

Another location, which isn’t as ideal, but could still work is the smaller green star on the left side. The issue with this spot is that the air in the hallway won’t be circulated nearly as much as with the first spot, but it is an option.

As you can see in both locations, they are more or less centrally located between the adjoining rooms. They are also on the edges, so they shouldn’t interfere with your home’s hustle and bustle.

Now, if you’re just putting your air purifier in a rectangular room, then you can stick it along one of the longer walls of the room near-ish the center. Again, this allows for the air purifier to most easily circulate all the air in the room and filter it.

But now there’s the question of how close to center should it be? Well, the answer is simple, have it as close to it as you can get it without messing up your whole room. It can sit beside your couch or on a shelf, or anywhere, really. All that matters is that it’s close-ish to the center point of your room.

And if it isn’t, it isn’t the end of the world! Trust me, you’ll still notice improved air quality if you buy a good air purifier no matter where you put it. My advice on putting it near the center of your room only helps you get the best possible air throughout the whole room.

Now, I think you understand what I’ve getting at, so I’ll drop a few more diagrams, these without the full write ups.

I’m sure you get the point now. It’s pretty straightforward!

What Should I Know Before I Get an Air Purifier?

There’s a lot to know about air purifiers before you get one, but it can more or less be boiled down to just three things, which I address in this article here. Just know what you want out of it, do you want the cleanest possible air, just dust removal, or are there health concerns you’re addressing? Next up, you need to know your budget to purchase the unit and finally, you need yo know how much you can afford to pay for replacement filters.

A lot of air purifier companies seem to charge way too much for replacement filters, so be sure to check how much one will cost you before you buy, if that’s a concern. A lot of replacement filters will cost between 5 and 40 dollars, but there are some that cost 80 or more (usually just for high end models that service a huge area).

Most air purifier filters will last about 6 months, so you will need to order a replacement twice a year. It might be cheaper to just order a bunch at once, if you have to pay individual shipping and if the company offers bulk discounts. Some air purifiers come with a few replacement filters, which can be really nice as well.

I’ve actually just got my hands on an air purifier that has a main filter that last for two whole years, which is pretty stinking neat as well. It’s built for large rooms (up to 1000 square feet) and is the best air purifier I’ve every used by far, and that’s saying a lot. If you’d like to check out my first article on that air purifier, then you can do so here.

Thanks for the read, and I hope this article helped you on your air purifier journey!

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Jonathon Silva

Jonathan Silva is our longtime Air Purifier Essentials author. He has been writing on air purification technologies for his entire professional career.

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