How Often To Change The Air Purifier Filter?

Want to know how often to change the Air Purifier Filter? We got you!

Air purifiers require some maintenance. However, the maintenance is very easy, and – at the end of the day – there is only one thing to check: the filters.

An air purifier with dirty filters not only doesn’t work but does more harm than good. When a filter is dirty, it can’t trap any more particles, and these are just blown back into the environment.

But it can also be worse than that: when the filter becomes very dirty, particles can detach from the filter itself and be blown into the environment: instead of cleaning the air, you’d be making it more polluted.

So, it’s important that you wash or replace the filters when it’s time. But when should you do it?

How Often To Change The Air Purifier Filter?

Key Takeaways

  • When you see an LED light blinking or an alarm appearing on the filter’s display, that’s when you know your filter is not working.
  • Some filters are washable and reusable.
  • You can change filters every four-six months.

Filter Replacement Alarm

washing filter

The ideal would be to buy an air purifier that features some kind of filter alarm.

A system (it could be a LED light, an alarm, or some text appearing on display) that lets you know when the filters aren’t working anymore.

When the filters aren’t working anymore, you can:

  • Wash them. However, not every filter can be washed, so always check if you can. Activated carbon filters, for example, can usually be cleaned. However, you can wash them endlessly: the day will come when you need to replace your washable filter.
  • Replace them. If you’ve washed the filter many times, if it is non-washable, you’ll need to replace the old filter with a new one.

Read: How Does An Air Purifier Work?

Read: What Are AOC Carbon Filters?

No Filter Replacement Alarm


If your air purifier isn’t equipped with a system that tells you when it’s time to replace the filter, you have a couple of options:

  • You can check your air quality monitor if you have one. When you start seeing that the air is not clean as usual when the device is on, it’s because it’s time to change the filters.
  • You can change them periodically: every 4 months is usually the most recommended frequency for replacing the air purifier’s filters. There are some filters that have a longer life; however: HEPA filters can be replaced every 6 months.

If you don’t use your air purifier every day, the frequency can be even longer. As a general rule, the more you use your air purifier, the more often you’ll need to change the filters.

Having some kind of system that tells you precisely when it’s time to change the filters is cost-saving.

How to Know its Time to Change the Filter?

replacing filter

Here are some tips that will help you determine that it is time to change the filter:

  • You notice a bad odor.
  • You start to see more pet hair in the air.
  • You and your family members have started to struggle with allergies even in the presence of your air purifier.
  • Your filter has started to look dirty and grey with all the build-up.
  • Your space is not as clean as before and has more dust circulating in.


The only maintenance that air purifiers require regards filters. You need to maintain them clean whether you can wash them or you need to replace them.

Because filters have a cost, the ideal is to change them only when needed.

Therefore, you buy an air purifier with a filter sensor that tells you when it’s time to change them, or you purchase an external air monitor to check how the device is working and, when it’s not, you change the filters.

Read: How Long Should I Run My Air Purifier?


When should I change my true HEPA filter?

You should change a true HEPA filter every 12 months or after 8,760 usable hours.

When should I change my Activated Carbon filter?

You should change a Activated Carbon filter every 12 months or after 8,760 usable hours.

Is cleaning the air purifier filter with water enough?

You can dust off & brush the filter followed by cleaning it with water, but this will damage the filter’s mesh fiber, so the purifier might perform to its best capability.

Changing the filter every 12 months is recommended.

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