How Long Does an Air Purifier Take to Clean a Room?

Whether you’re planning on buying an air purifier or have already got your hands on one – you might be wondering how long it actually takes for the unit to clean the air within your room.

After all, air purifiers run on electricity, and you don’t want to waste power by keeping it on if the air in the room is already as purified as it can be.

And so, in this article, we will take a look at all the details and give you an accurate answer, so you can have your air purifier turned on just enough to keep the air within your room clean without wasting any additional electricity.

Read on to learn more.

How Long Should I Keep My Air Purifier On?

Ideally, you want to run your air purifier for at least 12 hours a day for optimal results.

When you keep it on for 12 hours, it has enough time to filter out all the harmful particles and contaminants in the air in your room, which will lead you to experience a range of health benefits.

In fact, if you can, we’d even recommend keeping it on for a full 24 hours a day.

This is because dust and other particles are constantly entering your room through your windows and doors.

So, if you keep the air purifier on all the time, the unit will constantly filter out any particles and allergens that enter your room throughout the day and night.

With that said, if you don’t want to see an increase in your electricity bill, keeping your air purifier on around the clock might not be the best idea.

So, at the very least, keep it on for half the day – especially when there is a lot of movement in the room as that is when most of the dust and particles start circulating in the air.

Factors That Affect the Air Purifier Cleaning Time

The air we breathe is full of particles.

Even if you run an air purifier for a couple of hours a day, new particles will constantly enter the circulation of the purified air in the room.

This is why we recommend keeping the air purifier on for 24 hours for the best results.

But at the very least, you need to run your air purifier for 12 hours a day if you want to breathe clean air.

It’s no lie that cleansing the air within a room can take a while, even with the best air purifier.

And depending on certain factors, you may have to run your purifier even longer.

Here are some of the key factors that play a role in how long your air purifier will take to clean the air within your room.

Air Changes per Hour

Also expressed as ACH, this refers to how much air the purifier can clean in a room in an hour.

To give you a better understanding, a purifier that runs at 4 ACH can cleanse the air in your room twice as fast as a purifier running at 2 ACH.

Clean Air Delivery Rate

This is the official measurement used by AHAM to determine how efficiently an air purifier can clean a room. It can take a lot of effort and time to measure this by yourself.

So, it’s best to look at the description of your air purifier to see how fast it cleanses the air.

Filtration Type

The type of filtration on your air purifier can also affect how well it cleans a room.

Generally, the more filters the air purifier has, the better it can cleanse the air indoors.

That’s why we highly encourage reading about the filtration system of your air purifier to gain a better understanding of the type of filtration it is using.

Room Size

One of the most significant factors in determining how long it takes an air purifier to clean a room is the size of the room that the air purifier is within.

The smaller the room, the less air, which also means the less time it takes for the unit to clean the air.

So, if you plan on cleansing large rooms in your home, you may want to buy a bigger and more powerful air purifier that has the capacity to filter a large volume of air.

If you get an air purifier for a small room and turn it on in a big room, you may end up having to wait a pretty long time to feel the difference in the quality of the air you’re breathing.

Tips to Decrease Air Purifier Cleaning Time

Many factors can affect the time it takes to purify the air in a room. And in most cases, even after the purifier cleanses the air, you still have to deal with new particles coming in, especially if you leave the windows open.

So, if you don’t want to keep the air purifier running all day every day, there are some things you can do to allow it to clean the air faster and more efficiently.

This isn’t an alternative to keeping it on constantly, but it’s a great way to cut down on your power consumption.

And to help you out, we’ve compiled some of the most effective methods of reducing the cleaning time of an air purifier.

Close the Windows

First things first, you want to give the air purifier the easiest time possible.

That means trying to reduce the number of extra contaminants and particles entering the room you plan on cleansing.

So, the first step is to make sure to close all the doors and windows of the room.

While this won’t completely stop new particles from entering, it does reduce them to a great extent.

So, if you close all the windows and doors within the room, you will be able to reduce the time it takes for the air purifier to clean the air in the room.


Another thing you shouldn’t forget when you own an air purifier is maintenance. Even the most advanced models on the market require maintenance from time to time.

Remember, all the particles that the purifier absorbs stay inside the purifier, which means you need to clean it regularly.

If you don’t clean and maintain your purifier, it won’t work as efficiently.

And in turn, that means that it will take much longer for the air purifier to do its job.

So, if you’ve had the air purifier for a while, we recommend trying to clean and maintain the unit on a weekly basis to ensure it’s working to the best of its abilities.

Give the Purifier Space

If you have quite a large room, then finding space for the air purifier won’t be an issue.

However, if you want to keep the air clean within a smaller room – finding the perfect spot for the air purifier to maximize its effectiveness is of crucial importance. 

Ideally, you want to give the air purifier enough room to be able to suck in all of the surrounding air.

For that reason, if you put it right next to your sofa, it will only filter a very limited amount of air within your room.

So, typically – the best place for an air purifier is around the middle of the room or by the window or door where the newest air and particles will be entering from.

Use Multiple Air Purifiers

While this isn’t the most economical option, another thing you can do to decrease the air purification time of your room is to use multiple air purifiers.

For best results, you can try and place the two or more air purifiers in different corners of the room.

Do note that this option is best for cleaning the air within very large rooms that a single air purifier cannot handle alone.


While the amount of time you keep your air purifier running is important, you shouldn’t forget that consistency of using the unit is just as, if not more important.

You want to be breathing clean air as much as possible, and to do that, you need to turn your air purifier on every day, or at least whenever you plan on staying in that room.

And if you keep this in mind, it will be much easier for you to keep the air in your room clean, keeping your respiratory system healthy for a long time to come.