Keep in mind that most disposable air filters are undercut (this is an industry standard) from anywhere between ¼” to ½”. In most cases, you should be able to use the closest standard size. For example, an air filter measuring 15-3/4″ X 19-3/4″ exact, could be replaced with one that is 16″ X 20″.

How do I know what size furnace filter I need?

Usually, the filter size is printed along the edge of the filter’s frame. Note that the size listed in bold on the frame of the filter is the filter’s nominal size, which likely differs from its actual size.

What is the standard size air filter for a furnace?





10×20

What is the most common size furnace filter? Currently, the most common size furnace filters are 10×20. But should your system need custom sized air filters, note that we offer custom sizing ranging from 8 x 24 x 1 to 25 x 30 x 1.

How do I know which furnace filter to buy?

The easiest way to find out what size filter to get for your furnace is to simply remove your current filter and look at its dimensions. These are typically printed along one of the sides of your filter.

Does furnace filter size matter?

Why Furnace Filter Size is Important. Choosing the correct size for your filter will allow the filter to do its job properly. A filter that is either too small or two large, will create gaps around the filter, in turn allowing air to flow around the sides.

What size filter do I need?





Check the old air filter for its size

The first (and easiest) way to figure out your furnace filter’s size is to check your old air filter for its size. Most air filters have their size printed on the side of the frame. The length, width, and depth of the filter are measured in inches.

Do air filters have to be exact size?

In most cases, you should be able to use the closest standard size. For example, an air filter measuring 15-3/4″ X 19-3/4″ exact, could be replaced with one that is 16″ X 20″.

What is the most common filter size?

Here are some of the most common furnace and AC filter sizes:

  • 10 X 20 X 1”
  • 14 X 20 X 1”
  • 16 X 24 X 1”
  • 18 X 30 X 1”
  • 20 x 20 x 1.
  • 16 x 25 x 1.
  • 20 x 25 x 1.
  • 20 x 25 x 4.

Should a furnace filter fit tight?



A furnace filter should fit snug inside of your unit. If it is too loose, then air will still come in even while your furnace is running. On the other hand, if it is too tight, you may not be able to remove the filter when it is time to change (if that’s what you decide).

What happens if your furnace filter is too big?

The biggest concern when you use the wrong size air filter is that it may not effectively prevent dust from building up on your HVAC system’s motors and blowers. This dirties up your furnace which could affect its performance or possibly harm the system’s internal components, leading to costly repairs or replacements.

What happens if you use a furnace filter that is too small?

An improperly sized air filter doesn’t do its job. When it’s too small, it lets dust, mold, and other contaminants into your air vents. These then spew into your air, providing air quality problems.

Can you use a 1-inch furnace filter instead of 5?



If your system only fits a 1-inch or 2-inch filter, a high MERV rating could be detrimental. A 1-inch filter with less surface space will get clogged fairly quickly and need to be replaced much sooner than a thicker filter.

Are 2 inch furnace filter better than 1 inch?

Well, the thicker the filter the less restrictive it is. This contributes to a better flow of purified air. This means that 2-inch furnace filters allow a better flow of air than 1-inch filters.

Are 5 inch filters better than 1 inch?

Enhance Indoor Air Quality

Replacing your standard one-inch air filter with a pleated 5-inch filter can result in better air quality inside your home. That’s because bigger air filters feature higher MERV ratings, leading to better filtration of pollutants and allergens.

Are wider furnace filters better?



Most air filters are 1 inch thick, but some systems can accommodate filters 2 to 5 inches thick. In our tests, we found that the thicker the filter, the better it works and the longer the replacement intervals. That means it’s better for you and for your heating, ventilating, and air conditioning (HVAC) system.

Will a MERV 13 filter hurt my furnace?

MERV 13 air filters are the highest-rated air filters for home use. Any air filter with a rating higher than 13 will restrict air flow to the point of which could cause damage to your HVAC system, resulting in an added expense to fix it.

Is a MERV 12 filter too restrictive?

While the highest MERV ratings are the most effective for air quality, they can harm your HVAC system. A higher MERV rating means a higher resistance, which means less airflow.
So what does MERV stand for anyways?

MERV Minimum Particle Size
9–12 3.0–1.0 μm
13–16 1.0–0.3 μm
17–20 < 0.3 μm

Can a furnace filter be too restrictive?

Burnt out motors and controls can result from too-restrictive filters. Coils, motors, and blowers can also easily become clogged by weak filters creating higher fan usage resulting in higher energy costs.

Is no air filter better than a dirty one?



Running your air conditioner without a filter is worse than running it with a dirty one. Instead, get to the store as soon as possible for a replacement or call an HVAC professional for replacement. Without a filter, your air conditioner is at risk for severe and expensive problems.

Is MERV 11 OK for my furnace?

Increased usage can lead to more wear and tear, so make sure to regularly maintain your furnace. MERV 11 filters however, are not considered to be too high for residential use. Anything higher than a MERV 11 is designed for commercial or households with family members suffering from respiratory issues.