What Size Filter for a Carrier Furnace?

A furnace needs a filter to keep allergens out of your home and to help clean your air and heating system. If you have a Carrier furnace, and you're wondering about the filter size so you can get reserves for emergency replacement, you're in the right place. We have researched this topic for you, and we have all the information you need here.

Filter size depends on the Carrier furnace model you have. To determine your Carrier furnace's filter size, remove the filter and check for the dimensions printed on one side of the filter frame. If you can't find the nominal size, get the filter's actual size by measuring the filter frame using a measuring tape. 

Carrier furnaces come in different models, and they have different sizes of filters. Read on to get all the details you can't miss. We'll also discuss the difference between the nominal and actual size and what this means for you.

Technician checking the furnace, What Size Filter for a Carrier Furnace?

What Filter Size to Use for a Carrier Furnace?

There is no one-size-fits-all answer to this question. But in general, the filter size is determined by the specific Carrier model you are using. If you want to know the exact dimensions of your filter, simply remove it and look for its dimensions printed on the frame.

Huge Carrier logo at a Carrier manufacturer


Alternatively, you can measure the actual size of the filter using a measuring tape if you can't find the dimensions printed on the frame. Once you have the actual size figured out, round off the result to the nearest whole number. Voila! You should now get its nominal size.

What is the Difference Between Nominal Size and Actual Size?

The difference between the nominal size from the actual size is that the actual size is the real measurement of the filter, while the nominal size is the measurement you are allowed to use under the specs. 

Let's say the actual size includes these dimensions:

  • Length = 19.5 inches
  • Width = 19.5 inches
  • Thickness = 0.75 inch

The nominal size will comprise the following:

  • Length = 20 inches
  • Width = 20 inches
  • Thickness = 1 inch

Watch this video for a visual guide on measuring your furnace air filter size:

What are the Most Common Furnace Filter Sizes?

The most common furnace filter sizes are 20x20x1, 20x25x1, 16x25x1, and 16x20x1. For a more detailed description of each of these furnace filter sizes, kindly refer to the list below:

Filtrete 20x20x1 Furnace Filter

This filter will keep your air clean by removing particles such as pollen and dust from the air you breathe. This product is specially designed to fit the 20x20x1 furnace filter media.

Click here to see this Filtrete 20x20x1 furnace filter on Amazon

Filtrete 20x25x1 Furnace Filter

This furnace filter is specially constructed to meet the rigorous demands of a home air conditioning system. It features a MERV rating of 7, which ensures that the filter effectively captures particles as small as three microns, as well as large particles that can clog ductwork and vents.

Click here to see this product on Amazon.

Filtrete 16x25x1 Furnace Filter

Filtrete 16x25x1 furnace filters deliver superior filtration for improved air quality in the home or office. They feature a unique combination of MERV 7 rating, exclusive 3M technology, and non-electrostatic properties to provide the highest level of performance and protection from dust mites, allergens, and pollutants.

Click here to see this product on Amazon.

Filtrete 16x20x1 Furnace Filter

Filtrete 16x20x1 furnace filters are a convenient way to protect your home and family from harmful particles. When properly installed, these filters allow air to pass through them while trapping dust and other airborne particles, keeping them out of your home.

Click here to see this product on Amazon.

What is a MERV Rating for Furnace Filters?

MERV stands for "Maximum Efficiency Reporting Value." It is a rating system that ranks the efficiency of air filters. The higher the number, the more efficiently the filter captures smaller particles (measured in microns).

When deciding on a filter for a furnace, it's best to ask yourself what type of air pollution you expect to find in your home. The filter's MERV rating should be appropriate for the type of air pollution in your area.

For example, if you live in a neighborhood with high pollen counts and if you're allergic to pollens (with breathing difficulties), then you should choose a filter with a MERV rating higher than 7. But if you live in a place where air pollution is minimal, you can opt for a filter with a MERV rating somewhere between 1 to 4.

Why Do Higher MERV Filters Restrict Airflow?

A higher MERV rating means better air quality, but it also means compromised airflow. This is because a higher MERV filter has smaller openings than the lower-rated ones. These smaller openings allow for less airflow, causing the furnace to work harder than it should.

Is a Thicker Furnace Filter Better?

If you're looking to save money from the constant replacement of furnace filters, you might be wondering whether a thicker filter is more cost-efficient than a thinner one. A test conducted by Consumer Reports shows results that thicker filters are more efficient.

Thicker filters are most likely to extend the replacement cycle of your filter. Not only is this good news for your pocket, but it is also great news for your furnace at the same time.

Can You Run Your Furnace Without a Filter?

Technician repairing the furnace

The main function of a furnace is to warm your home, especially during winter. If you have a filter installed in your furnace, it will remove the particles that are generated as your furnace runs. A properly functioning furnace needs a filter to keep your indoor air quality high. This is especially true if you have pets or children.

Pets shed hair and fur, which will get into the air ducts and become a part of the airflow in your house. When you have pets at home, the pet hairs and fur will collect on your furniture and carpet.

Not only do pet hairs make your home untidy, but they may also cause allergies. This is why you should ensure your furnace has a working filter installed.

In addition to pet hairs, dust mites can be a pain to deal with. Dust mites tend to thrive indoors because they like warm temperatures. They also thrive in areas where there is a lot of moisture. Dust mite allergy can cause problems like runny nose and sneezing. It can also lead to asthma.

If you spend more than two hours a day inside the house, then you are exposed to the majority of the allergens that are floating around, that is if you don't have a filter in your furnace. This is why it is important to have a furnace filter with a high MERV rating.

How Often Should You Change Your Furnace Filter?

Generally, filters should be changed once every three months. However, if you are using a thinner filter than what is recommended by the manufacturer, it may necessitate you to change it earlier than the average three-month interval.

Thicker filters trap dirt and dust better than thinner filters. They can save you money from replacing your filters too soon because they have more room to trap dirt and dust.

Can You Vacuum Clean a Furnace Filter to Save Money for Replacement?

Vacuum cleaning a filter to save money from regular filter replacement can be done, but it is not recommended. While it is true that you may be able to save a few dollars by cleaning and reusing a filter, doing so may result in damaging the furnace.

This is because vacuum-cleaning a dirty filter won't totally remove all the dirt and dust and there will always be that stubborn dirt that is stuck in the fibers. If you keep on doing this every time you're supposed to replace a filter with a new one, the reused filter will accumulate dirt and will eventually clog the filter.

On top of compromised air quality, reusing a clogged filter over and over again can restrict airflow, causing unnecessary stress to the furnace. If tolerated long enough, a reused filter can shorten the lifespan of a furnace.

In Closing

Technician checking the furnace

A furnace filter helps reduce dust, debris, and allergens that can cause allergy attacks. The filter size is important because it can affect the furnace's efficiency and can also change the airflow through your home.

Now that we have discussed in detail everything you need to know about your Carrier furnace filter size, it's time to check out related articles that you may find interesting.

But before you do that, why not leave a comment in the comment section below and share with us your thoughts on this topic? We'd love to hear from our readers!

Suggested readings:

How To Clean Rheem Furnace Filter

Can You Clean Home Air Filters Or Should You Replace Them?

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