How often you should change your AC filter

It's more often than you think.

Alina Bradford
Alina Bradford CNET Contributor
Alina Bradford has been writing how-tos, tech articles and more for almost two decades. She currently writes for CNET's Smart Home Section, MTVNews' tech section and for Live Science's reference section. Follow her on Twitter.
2 min read
HVAC disposable air filter
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Your central air conditioning filter is an important tool for reducing your home's allergens and keeping it a little more dust-free. Many HVAC filters actually say on the packaging that a once-a-month schedule is a good idea to keep dust and allergens to a minimum.

You probably already know you should change your filter on a regular basis, but what you may not be aware of is exactly how often that frequency can vary from household to household. Here's what you need to know to keep your home's air clean -- and even save some money, too.

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Some filters last longer than others, so be sure to take a look at the packaging. All filters have a Minimum Efficiency Reporting Value (MERV) rating. The higher the MERV number, the better quality the filter is, meaning it can hold contaminates better and last longer.

The only downside to picking a filter with a high MERV rating is that it can slow down the airflow in your AC unit. The best choice is a balance between good quality and good airflow, which is typically a filter that has a MERV rating of 6 to 8. If you have a high efficiency AC, you may get away with a higher rating. Check the owner's manual to be sure.

Change up the time frame

Now that you have a good filter, there's a mix of factors that affect how often you replace it. Every three weeks is a good rule of thumb if you have multiple pets, live in a very dusty or polluted area or have severe allergies.

On the other hand, if you rarely use your AC, you can wait up to six months to change the filter. A good way to remember is to switch it out once in the spring and once in the fall.

There are a lot of variables, right? The only way you can be sure you're changing your filter at the right time for your home is to give it a peek once a week to get a feel for how quickly it gets dirty. Hold it up to the light and if you can't see light through the filter, then it is definitely time for a new one.

An added perk

Not only does changing your AC filter help your home's air conditions, it can also save you money. Replacing a clogged air filter with a new one can lower the air conditioner's energy consumption by 5 to 15 percent, according to the US Department of Energy. Less energy consumed equals a lower power bill, which is a big win in the dead of summer when those electricity costs normally spike.

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