The Ultimate Guide to Furnace Filter Sizes: Pleated vs. Non-Pleated Filters

Do you know the difference between pleated and non-pleated furnace filters? If not, you're not alone. Many homeowners may not realize that the type of filter they choose can have a significant impact on their indoor air quality and the efficiency of their furnace.

That's why we've created this ultimate guide to furnace filter sizes, with a focus on pleated vs. non-pleated filters. We'll explore the benefits and drawbacks of each type, and help you determine which one is right for your home and your furnace.

So whether you're a first-time homeowner or a seasoned DIY-er, this guide is for you. Keep reading to learn everything you need to know about furnace filter sizes and types.

Understanding Furnace Filter Sizes

Choosing the right furnace filter size is essential to ensure the efficient operation of your heating and cooling system. Furnace filters come in a variety of sizes and thicknesses, and selecting the right one can be confusing.

The first step towards understanding furnace filter sizes is to locate the filter rack or slot. Typically, the filter rack is located just inside the HVAC unit, although it may also be placed in the return air duct.

Once you have located the filter rack, measure the length, width, and depth of the filter slot. These dimensions will give you an idea of the size filter you require.

It is important to note that not all furnace filters are the same size, and using an incorrect filter size can cause poor airflow and reduce the efficiency of your heating and cooling equipment.

Before purchasing a filter, ensure that it is the correct size for your system. Some filters may require a slightly different size than your current one, so it is important to double-check before purchasing.

Finally, ensure that the filter you select is compatible with the airflow capacity of your system. Filters with high MERV ratings may be more effective at trapping dust and allergens, but they can also reduce airflow, causing your heating and cooling system to work harder, lowering its efficiency, and increasing your utility bills.

In conclusion, understanding furnace filter sizes is crucial for maintaining the optimal operation of your HVAC system. Take the time to measure your filter rack and ensure that the filter you purchase is the correct size for your system, and compatible with its airflow capacity.

What Are Pleated Filters and How Do They Work?

Pleated furnace filters have become increasingly popular among homeowners due to their improved filtration capabilities. These filters are made of polyester or cotton fibers, which are pleated to create a greater surface area. This enables them to capture more dust, dirt, and other contaminants than non-pleated filters.

When air passes through the filter, the pleats create a maze-like structure that forces air to move in different directions. This increases the contact time between the air and the filter, allowing more pollutants to be trapped before the air is released into the environment.

Pleated filters also have a higher MERV (Minimum Efficiency Reporting Value) rating. This is a measure of a filter's ability to trap airborne particles. The higher the MERV rating, the more effective the filter is at capturing pollutants. Pleated filters typically have a rating of 8-13, while non-pleated filters have a rating of 1-4.

Overall, pleated furnace filters offer several advantages over non-pleated filters. They are more efficient at capturing airborne contaminants, have a higher MERV rating, and need to be replaced less frequently. However, they do come at a higher initial cost. If you're looking for an air filter that can offer improved air quality and protect your HVAC system, a pleated filter may be the best choice for you.

Non-Pleated Filters: Pros and Cons

Non-pleated filters are an alternative to pleated filters in homes and buildings. These filters have their own set of pros and cons compared to their pleated counterparts.


One of the main advantages of non-pleated filters is that they are typically less expensive than pleated filters. This can be an attractive option for homeowners on a budget or those who want to save money on filter replacements.

Non-pleated filters are also typically thinner than pleated filters, which can make them easier to install and store. They can also provide more airflow, which can be helpful for those who need a lot of air circulating through their home or building.


Compared to pleated filters, non-pleated filters typically have a lower filtration efficiency. This means that they may not be as effective at trapping dust, dirt, and other particles in the air. This can lead to a decrease in indoor air quality and potentially exacerbate respiratory issues.

Non-pleated filters also typically need to be replaced more frequently than pleated filters. This can add up in cost over time, potentially negating the initial cost savings when purchasing non-pleated filters.

Additionally, non-pleated filters may not be suitable for all HVAC systems. It is important to consult with a professional HVAC technician to determine which type of filter is best for your specific system and needs.

Overall, non-pleated filters can be a cost-effective and convenient option for homeowners and buildings with the right HVAC system and filtration needs. However, those who prioritize air quality and filtration efficiency may want to consider the benefits of pleated filters instead.

Pros and Cons of Pleated Filters

Pleated filters have become a popular choice for many homeowners due to their higher efficiency in trapping dirt, dust, and allergens compared to non-pleated filters. However, like anything else, there are pros and cons that come with using pleated filters.


  • Higher filtration efficiency: Pleated filters have a larger surface area than non-pleated filters, allowing them to capture more particles.
  • Improved air quality: With higher efficiency in capturing particles, pleated filters can improve the indoor air quality of your home, making it safer for those with allergies or respiratory issues.
  • Long-lasting: Pleated filters can last up to three months, depending on usage and the level of contaminants in your home’s air.


  • Higher cost: Pleated filters are generally more expensive than non-pleated filters due to their higher efficiency and longer lifespan.
  • Restricted airflow: Due to their denser structure, pleated filters can reduce the airflow in your furnace, leading to decreased heating efficiency.
  • Unsuitable for older furnaces: Some older furnaces may not be compatible with pleated filters due to their restricted airflow, which can cause damage to the furnace.

It is always recommended that you consult with an HVAC professional on the best filter size and type for your furnace system. Considering the pros and cons of pleated filters can help you make an informed decision that will meet your home’s air filtration needs and budget.

Choosing the Right Filter for Your Furnace

When it comes to choosing the right filter for your furnace, there are a few key factors to consider:

  • Filter size: Make sure you choose the right size filter for your furnace. You can check the current size by looking at the filter that's already inside the furnace or by checking the owner's manual.
  • MERV rating: The MERV rating determines how efficiently the filter captures particles. Generally, the higher the MERV rating, the better the filter is at removing pollutants from the air. However, filters with high MERV ratings can also restrict airflow and put additional strain on your system. Consider a filter with a MERV rating between 8 and 11 for the best balance between air quality and system performance.
  • Filter material: There are two main types of filters: pleated and non-pleated. Pleated filters have more surface area and are better at capturing small particles, while non-pleated filters are generally more affordable. Decide which type of filter is best for your needs and budget.

It's also important to replace your filter regularly. Most filters should be replaced every 1-3 months, depending on usage and the level of pollutants in your home. A dirty filter can restrict airflow and reduce system efficiency, so make sure to keep up with regular maintenance.

Overall, choosing the right filter for your furnace can help improve air quality in your home and keep your system running smoothly. Consider the size, MERV rating, and material when selecting a filter, and make sure to replace it regularly to keep your system in top condition.


Choosing the right furnace filter size is crucial for the efficient functioning of your HVAC system. Whether you opt for a pleated or non-pleated filter, it is essential to make sure that it fits properly and is replaced regularly. Pleated filters offer better air filtration by trapping a higher percentage of small particles, while non-pleated filters are more affordable and have a lower resistance. By considering your specific needs and preferences, you can make an informed decision and enjoy a warm and clean indoor environment all year round.

Frequently Asked Question

It's important to know the size and type of furnace filter you need before replacing it. This is because different furnaces require different sizes of filters. Your brand of furnace may need an electrostatic or media filter of a particular size - so make sure to check your old filter for these details.

Replacing your filter regularly can save you money in the long run. It helps your HVAC system become more efficient, and also keeps the air quality high. So, what are the most common furnace filter sizes?

The most popular furnace filters come in the following dimensions: 10x20, 14x20, 16x24, 18x30, 12x12, 14x24, 16x25, 20x20, 12x20, 14x25, 18x18, 20x24, 12x24, 14x30, 18x20, 20x25, 12x30, 15x20, 18x24, 20x30, 12x36, 16x20, 18x25, 24x24 and 25x25. You can use your existing filter as a reference guide to find the perfect size for your furnace. The filter dimensions should be printed on its frame as length x width x height.

In conclusion, it's important to know your furnace filter size before you replace it. Doing so will improve your HVAC system's efficiency and save you money in the long run. Plus, a clean filter is key to keeping your air quality high.

When it comes to furnace filters, exact size matters. If you get a filter that is too small or too big, air will flow around it instead of through it, meaning not all of the air will be filtered. That's why it's essential to use the right size filter for your HVAC unit.

Here's what you need to know: the size of the air filter is typically listed in the big, bold font on the packaging, which is known as the nominal size. This is a rounded-up whole-number version of the actual size, which is written in the fine print on the filter's frame. That's usually 0.25'-0.5' smaller than the nominal size, and the actual measurements of the filter may vary slightly depending on the brand.

In some cases, less common sizes come true to size, meaning the nominal size is the same as the actual size. When that's the case, it's usually noted with “actual size” in parentheses on the filter's frame.

So, the verdict is in: the answer to the question 'Do furnace filters have to be exact size?' is a resounding yes! Be sure to get the right size air filter for your system to ensure it runs smoothly and that you reap all the benefits your filter has to offer.

Are you looking for the best furnace filter? Look no further! Our team of experts at This Old House Reviews have researched the top five furnace filters on Amazon to help you find the perfect one for your HVAC system. Plus, these products are available at local home centers or online retailers like Amazon.

A great furnace filter can make all the difference. It will keep your HVAC system running smoothly, potentially leading to lower electricity bills and better air quality. That's why we've taken the time to compile a list of the best furnace filters for you.

At the top of our list is the Filtrete furnace air filter. It promises to last up to three months and outperform filters made with fiberglass. Plus, it can capture 64% of airborne particles like pet dander and pollen. This filter also comes with instructions for easy installation on HVAC systems that require filters 20 by 25 by 1 inches in size.

Customers love this furnace filter. They find it easy to install, sturdy, and a great value. However, some customers have faced difficulties with Filtrete’s app.

When choosing a furnace filter, make sure to take into account its size, filtration level, and material. That way, you can get the best filter for your specific needs.

Changing or replacing your furnace filter is one of the best ways to maintain a healthy, efficient HVAC system. But you need to make sure that you're using the right filter for your system. Here's a step-by-step guide to help you pick the perfect one!

First, measure the dimensions of your existing filter. This will tell you the length, width, and depth you need. The easiest way to do this is to look at the existing filter and buy the same size.

Next, you need to choose the right MERV rating. The MERV scale ranges from 1-20 and measures the filter's effectiveness at catching particles in the air. The higher the value, the more effective the filter is at trapping particles, but it also means less airflow.

Now it's time to decide on the type of filter. There are many options available, so take some time to research the best type for your system.

Once you have everything you need, it's time to install the filter in your furnace/air handler slot. Remove the old filter to make room for the new one.

Finally, make sure to replace your filter regularly. If it clogs up with dust and particulate, it can reduce airflow and become ineffective.

Furnace air filters are essential for your heating system. You should replace your filter at least once every three months. So, how do you select the best furnace filter for your needs? Let us help you out!

Generally, furnace filters are made up of a cardboard frame, fiberglass filter, and metal mesh. These materials work together to strengthen the filter and protect your HVAC components from dust and debris. Plus, they also help improve the air quality in your home. Without a filter, your HVAC system could become dirty and its performance would suffer.

As air passes through the furnace filter, it traps and catches any contaminants. If you don't replace or clean your filter regularly, it can obstruct airflow and cause damage to your HVAC system. In most cases, you should change your furnace filters every three months. However, you may want to replace them more or less often depending on the situation.