4‑Inch vs 1‑Inch HVAC Filters: Which is Best in Phoenix?

The short answer? A 4-inch filter will last longer and provide better air quality for your home.

The long answer? The “best” filter option for you really depends on your:

• Budget: Are you willing to spend the extra money on a 4-inch filter?
• Needs: Does your home have allergy or asthma suffers that need the better air quality of a 4-inch filter?
• Maintenance preferences: Do you mind changing a 1-inch filter every month? Or would you prefer changing a 4-inch filter every 3–6 months?
• System: If your system calls for a 1-inch filter, you’ll need to pay a professional to alter your system to accommodate a 4-inch filter.

Note: Forcing a 4-inch filter into a system that uses a 1-inch filter can decrease the filter’s efficiency and seriously damage your system. So, yes, paying a professional to alter your system will add to your cost, but it’s not something you want to forego.

To help you decide which depth of filter to get, we’ll compare 1-inch and 4-inch filters in terms of:

We’ll go over these factors in more detail.

If improving air quality is a priority for you, the depth of the filter doesn’t matter so much as MERV.

But be warned, if you go with a higher-MERV filter, you’ll want to make sure that you stick with the thicker, 4-inch option.

We’ll explain.

MERV (Minimum Efficiency Reporting Value) is a rating that indicates how well an air filter can collect particles in your home’s air.

The higher the MERV rating, the smaller the contaminants a filter can trap—which also means it will clog faster.

That said, a thinner 1-inch filter with a high MERV rating would clog very quickly (compared to a 4-inch pleated filter) since there is less surface area available to trap contaminants.

Warning: A clogged, high-MERV filter can increase your energy bills but more importantly, it can cause expensive damage to your HVAC system.

For this reason, you might want to go with a 4-inch HVAC filter to improve your home’s air quality.

Plus, 4-inch filters generally have higher MERV ratings than 1-inch filters (there is some overlap). You can find:

• 1-inch air filters with MERV ratings anywhere from 1 to 13
• 4-inch air filters with MERV ratings of 8 to 16

Going with a 4-inch filter would mean you’d get a filter with at least a MERV 8 rating, which would remove contaminants down to 3 microns (a unit of measurement), including dust mites and some types of pollen. (For context, a human hair is 50 microns.)

But if you have allergy or asthma sufferers in your home, you might want to go with a MERV 13. A MERV 13 filter will effectively remove allergenic contaminants down to .3 microns, like:

• Pet dander
• Bacteria
• Some viruses
• Tobacco smoke
• Smog

You’ll change 4-inch filters a lot less than 1-inch filters.

Why? Well, 4-inch filters have larger pleats. That means they have more surface area to catch particles, making them last 3–5 times longer than 1-inch filters.

Most HVAC technicians recommend changing 1-inch air filters every 30 days, while 4-inch filters can be changed every 3–6 months. Some 4-inch filters can even last up to a year.

Note: You’ll change your HVAC air filter more often if it has a higher MERV rating, the place you live has low air quality, your home gets a lot of traffic and/or you have pets.

When it comes to cost, a filter’s MERV rating is a bigger factor than its depth.

On average:

• High-MERV (8–16) filters cost $25–$55
• Low-MERV (1–7) filters cost $5–$20

But the depth of the filter still plays a role in how much you’ll pay in the long run.

For example, since you’ll change 1-inch high-MERV filters more often than you will 4-inch filters (see the maintenance section above), you could actually save money with a 4-inch filter—depending on what MERV you get.

For example, let’s say you use a 1-inch high-MERV filter that costs $10 per filter. If you replace your air filter every month (which you should do), you’ll spend roughly $120 throughout the year.

Now, compare that to a 4-inch filter. If you spend $40 on a 4-inch filter that needs to be changed every 6 months, you’d spend about $80 a year.