A good rule-of-thumb is to replace your filter every 1–3 months.
That said, some filters need to be changed more frequently than others because they get dirtier faster.
The important thing is to change your AC filter before it gets clogged with dirt and debris.
Why? A filthy AC air filter can cause issues like:
- Expensive energy bills
- Increased wear and tear on your AC system
- Ice buildup on your AC
- Frequent breakdowns
In this blog, we’ll share how to tell exactly when you should change your filter.
Need a pro to help you change your filter?
How to know how often you should change your AC filter
An air filter’s MERV rating will indicate how often you need to change your filter.
MERV (Minimum Efficiency Reporting Value) is a rating that tells you how effective an air filter is, or more specifically, how well it can catch particles in your home’s air.
The higher the MERV rating, the more effective the filter. Generally, low-MERV filters can last longer because they don’t collect as many particles as high-MERV filters.
Below are some more specific guidelines for replacing your air filter based on its MERV rating:
- MERV 1–4 filters: Every 3 months (or every other month during the summer)
- MERV 5–8 filters: Every 1–2 months (or monthly during the summer)
- MERV 8+: Check every month and replace if dirty
Note: These recommendations assume your air filter is less than 2 inches thick. If you have a filter thicker than 2 inches (which is recommended for most MERV 8+ filters), you can usually wait longer to replace your filter.
How to find your air filter’s MERV rating
Most manufacturers will include the MERV rating and dimensions of the filter on the long side of the filter (see an example here).
Sometimes, instead of “MERV 6” the filter might just say “M6”.
Can’t find your filter’s MERV rating? Contact a professional for help.
Other considerations that affect how often you should replace your AC filter
You should change your filter more frequently than the general recommendations we provided above if any of the following apply to you:
- You have pets
- Someone in your home suffers from allergies
- You keep your windows/doors open frequently
- Someone in your home smokes
- Your home is always dusty
Want specific air filter advice for your AC? Contact a San Antonio pro
If you want to avoid the hassle of changing your filter, consider joining our Pro Plus Advantage Member Plan.
When you join our Pro Plus Plan, we’ll check your filter for you during a routine AC check-up. If your filter is dirty, we’ll replace it for you.
In addition to filter replacements, by joining our Pro Plus Plan you’ll also get benefits like:
- 10% discount on repairs
- Priority scheduling
- An annual whole-house plumbing check
- And much more