How to Properly Size Your Air Purifier

The air inside your home is dirtier than the air outside, which makes an air purifier a worthy investment. Choosing the best model for your needs though doesn’t only mean that you have to look for one that has as many relevant features as possible. The area that it can cover is just as important, and it should match the area of the room you’re planning to purify. If you don’t make the right choice from this point of view, you might end up with a unit that isn’t able to efficiently clear the air of airborne contaminants.

As believers of the benefits of having an air purifier at home, we don’t want this to happen to you. This is why we’ve laid out the following guidelines to ensure that you’re spending your money on a properly-sized air purifier.


First things first: establish where you’re going to place the air purifier. Most buyers who are new to the world of air purifiers would usually purchase a single unit at first (just to try it out) even though they’re planning to use it inside different rooms at different times of the day. If this applies to you, it’s best to shop for a model that will fit the largest or dirtiest area you’re planning to purify. Note, however, that you’d have to purchase an air purifier with adjustable speed so you can switch to lower speed levels once you bring the unit to a smaller room.


Next, you have to determine the square footage of the area you wanted covered by your purifier. Measure the length and width of the area and multiply these two numbers together to calculate the square footage. Look for a model whose area coverage matches that of your room. If you can’t find an air purifier that’s an exact match in this regard, it’s best to be conservative and size up.

Getting an air purifier that’s rated for a smaller area will result to inefficient purification. You risk the air purifier not being able to give you the results that it’s promised. Not to mention, you might overwork the machine and compromise the lifespan and performance of its filters.

On the other hand, running an air purifier that’s been designed for spaces that are much larger will result in unnecessary power consumption and can consequently rack up massive power bills unnecessarily.

Pollution Levels

You will also want to consider the level of pollution in the area you want to purify. If there are constant sources of pollution in the area (for example, maybe your pets usually stay in there or it’s a very well-used kitchen), we recommend that you go with a model that can make between 2 and 6 air changes per hour (look for the air change per hour, or ACH, rate). There isn’t an exact formula in determining the level of pollution inside the room in question, so you’ll have to use some intuition in this regard.

Personal Needs

When sizing an air purifier, you’d also have to think about whether you’re trying to battle certain afflictions. We generally recommend an ACH rate of at least 4 if you’re an allergy or asthma sufferer, bot for those with severe asthma or allergies, the higher the ACH number is, the better.

The ACH number of an air purifier changes depending on the size of the room that it’s in. For example, let’s say you’re looking for an air purifier for your 500 sq. ft. bedroom. One model might be advertised as being for rooms that are up to 500 sq. ft., but a closer look at its specs reveals that its ACH rate inside a 500 sq. ft. room is just 2. This means that you’ll reach an ACH rate of 4 only if you use it inside a room that’s no bigger than 250 sq. ft. If you suffer from respiratory problems, this model might not offer the ACH you need.

Final Thoughts

Picking the right air purifier size for your space means considering the specifications of your individual space and the requirements that meet your personal needs. You need to consider the nature, size, and pollution level of the room you’re intending to clean when sizing an air purifier. You might have to cater to special ACH recommendations if you’re prone to allergies and asthma, too. This might seem like a complicated process, but it will ensure that you’re buying what’s best for your space and your needs.

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