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You’re standing in the aisle with the HVAC filters at the home improvement store looking at your options. There’s only one problem: you don’t know which one is best for your system. But you’re about to find out! Today, we’ll help you make important decisions for your HVAC system, including a 4″ vs 1″ HVAC filter and what’s best for you. 

We’ll also cover other important HVAC topics like what it means to have a HEPA filter and what MERV means. So, let’s get started!

4″ vs 1″ HVAC Filters: Is Bigger Better?

Before we get into specific considerations to help you decide between 4″ vs 1″ HVAC filters and other options, let’s talk about another important point to consider: MERV.

What is MERV?

Let’s turn to the EPA for a definition:

“Minimum Efficiency Reporting Values, or MERVs, report a filter’s ability to capture larger particles between 0.3 and 10 microns (µm). 

  • This value is helpful in comparing the performance of different filters
  • The rating is derived from a test method developed by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) [see].
  • The higher the MERV rating the better the filter is at trapping specific types of particles.”

a table of information about particle size

(Image Source: EPA)

While it might not be convenient to remember these numbers when you’re standing at the home improvement store, there is another option: look for a HEPA filter. When a HVAC filter is marked with “HEPA,” this means it is a high efficiency particulate air [filter].

As the EPA elaborates:

“This type of air filter can theoretically remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 microns (µm). The diameter specification of 0.3 microns responds to the worst case; the most penetrating particle size (MPPS). Particles that are larger or smaller are trapped with even higher efficiency. Using the worst case particle size results in the worst case efficiency rating (i.e. 99.97% or better for all particle sizes).”

MERV Ranges and Contaminants

You might also be curious about what these MERV ratings mean for specific contaminants in your home. For example, if you’re a pet owner, you’ll be particularly interested in what kind of filter will help keep your air clean and clear of this particular contaminant. 

Here’s a helpful guide to consider:

A 1″ HVAC filter with a MERV range between 1-13 can filter:

  • Pollen
  • Cockroach debris
  • Spray paint dust
  • Dust mites and dust mite debris
  • Carpet fibers
  • Sanding dust
  • Textile fibers
  • Mold spores
  • Hair spray
  • Cat and dog dander
  • Dusting aids
  • Fabric protector
  • Pudding mix
  • Legionella
  • Lead dust
  • Humidifier dust
  • Auto emission particulates
  • Milled flour
  • Nebulizer droplets

On the other hand, a 4″ inch filter with a MERV rating between 8-16 can filter out the aforementioned contaminants as well as:

  • Bacteria
  • Several viruses
  • Cooking oil
  • A variety of smoke and insecticide dust
  • Droplet nuclei (for example, from a sneeze or cough)
  • Most paint pigments
  • Most face powder

Now, what does all of this information mean for you? Most significantly, it means that filter size isn’t necessarily as important as MERV. If a filter’s MERV rating is high enough to create clean, high-quality air in your home, the size isn’t what matters most! 

4″ vs 1″ HVAC Filters: Primary Considerations

But with all of that being said, we know you still have questions about 4″ vs 1″ HVAC filters and choosing what’s right for you. So, let’s talk about the four big considerations to keep in mind.

  1. Budget
  2. Needs
  3. Maintenance
  4. System requirements


When you purchase a 4″ filter over a 1″ filter, you’re likely to pay more. That’s because 4″ filters last longer and they also provide better air quality for your home. So, even though they cost more than a 1″ filter, theoretically the costs can level out since they will last longer than a cheaper filter. 

Another way to look at this is that a filter with a higher MERV rating will also cost more than one with a lower rating. So, again, it isn’t so much about depth as it is the efficiency of the filter. A high MERV filter (between eight and 16) will typically cost between $25 and $55. On the other hand, a low MERV filter (between one and seven) will typically cost between $5 and $20. 

Of course, budget shouldn’t be your only consideration when it comes to choosing a 4″ vs. 1″ filter. 


You will also want to consider the unique needs of you and the other people who live in your home.

Do any of you suffer from allergies, asthma, or other health issues that benefit from cleaner air? In this case, opting for a thicker filter with the highest MERV rating you can find is ideal. However, even if you don’t have people with health issues, virtually everyone can benefit from better air quality! 

If you have pets in your home, this is another sign that a higher quality filter is the right choice for your home


We mentioned before that a filter with a greater depth won’t need to be changed as often as a thinner filter so this is something else to keep in mind when you’re deciding between different HVAC filter options.

If you go for a less expensive 1″ filter, be prepared to change it more frequently (every month). On the other hand, with a 4″ filter, you can expect to change it about every three to six months.

If you’re not prepared to change your filter each month (and if your system allows it) this is another surefire sign a 4″ filter is right for your system. 

System requirements for 4″ vs 1″ HVAC filters

Finally, you absolutely need to consider what’s right for your HVAC system when it comes to 4″ vs 1″ HVAC filters. Even if you would prefer a 4″ filter, if that won’t fit in your system, you’ll be doing more harm than good by opting for this filter depth. 

If you force a 4″ filter into a spot meant for a 1″ inch filter, your air quality can suffer significantly. At the same time, you risk causing serious damage to your HVAC system. 

What about your energy bills?

Finally, you might also be wondering what these different options can mean for your energy bills each month. Granted you change them on a regular basis that’s appropriate for the contaminants in your home, you shouldn’t notice a significant change in your energy bills between using a 4″ vs 1″ HVAC filter.

That being said, if you force a 4″ filter into a 1″ filter spot, this can have an impact on your energy bills. Your system will be less efficient, and ultimately work harder which means your energy bills will go up unnecessarily. 

Additionally, if your 4″ filter is clogged, it’s bound to tax your HVAC system more than a clogged 1″ system. This, again, highlights the importance of changing or cleaning your filters on a very regular basis!

In summary

As for that big question, “Is bigger better when it comes to a 4″ vs 1″ HVAC filter?” The answer is usually, yes. However, it’s not necessarily the right choice if your system is built for a one-inch filter. However, if both options work in your system and you’re willing to spend a bit more on a 4″ filter (although you won’t need to change it as often!), then a four-inch filter is the best choice. 

How Can We Help?

Do you have other questions about your HVAC system that we can help with? Contact us today if you are noticing:

  • Your energy bill is increasing
  • Your system is producing unusual sounds or smells
  • The system is refusing to turn on or cutting on and off
  • Your HVAC is failing to heat your home evenly

Regardless of the problems your heating system is having, the well-trained technicians of A/C Care Heat and Air can assess its condition and fix any issue. We’ll provide you with a prompt and thorough solution that will restore your comfort. Whether your system needs a quick fix or a total overhaul, we have the tools and expertise to get the job done right the first time.

If you aren’t comfortable changing your HVAC filters yourself or you’re still unsure which option to choose, we can help with that too. No problem is too big or too small for us!

Call us today to find out how we can help. 

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