What is the Standard Size for a Furnace Filter? Discover the Best Furnace Filter Sizes for Your Home

Are you tired of constantly replacing your furnace filter but unsure of what size to buy? Look no further! In this article, we will dive into the standard sizes for furnace filters and help you discover the best fit for your home. Say goodbye to constantly guessing and hello to cleaner air and lower energy bills.

The size of your furnace filter is crucial in maintaining the air quality in your home. A filter that is too small will not be able to capture all the debris and pollutants, while a filter that is too large will not properly fit and require constant adjustments. We have done the research and compiled a list of the most common sizes and their corresponding systems to ensure a perfect fit.

Not only will the right filter size improve the air quality in your home, but it can also save you money on your energy bill. A clean filter can improve the efficiency of your heating and cooling system, resulting in lower energy consumption. So, whether you are a new homeowner or just looking to upgrade, finding the right size filter is a small investment that can make a big impact. Let's get started!

The Importance of Choosing the Right Furnace Filter Size

Choosing the right furnace filter size is crucial for maintaining a healthy and efficient HVAC system in your home. A filter that is too small or too large can cause problems for your furnace, leading to decreased efficiency, increased energy bills, and even system damage.

The first step in determining the proper filter size is to check your furnace's owner's manual or specifications. These documents will typically provide guidance on the appropriate filter size based on the furnace's model and air flow requirements.

If you don't have access to the furnace's specifications, an HVAC professional can help you determine the correct filter size based on the dimensions of your furnace and the amount of air it circulates.

It's also important to note that there are different types of furnace filters available, each with their own unique capabilities and sizes. For example, high-efficiency filters may require a larger size to accommodate their increased filtering capacity.

Overall, taking the time to choose the right furnace filter size can help improve the air quality in your home, extend the life of your HVAC system, and save you money on energy bills in the long run.

Standard Sizes for Furnace Filters

When it comes to choosing the right furnace filter for your home, finding the right size is critical. Most filters come in standard sizes, which can make it easier to find the right one for your system.

Here are the most common standard sizes for furnace filters:

  • 16x20 inches
  • 16x25 inches
  • 20x20 inches
  • 20x25 inches
  • 24x24 inches

Keep in mind that these sizes may vary depending on the manufacturer and the type of filter you choose. It's always important to double-check the size of your current filter before purchasing a replacement.

If you're unsure which size filter to choose, consult your HVAC technician or refer to your system's owner manual. Choosing the right size filter will ensure proper airflow and optimal performance from your furnace.

Now that you know the most common standard sizes for furnace filters, it's time to replace your old filter and improve air quality in your home!

How to Measure Your Furnace Filter Correctly

Measuring your furnace filter size correctly is important to ensure you purchase the right filter for your heating and cooling system. Here's a step-by-step guide on how to do it correctly:

Step 1: Turn off your furnace to avoid any safety hazards.

Step 2: Locate your current furnace filter. It's typically found between the return air duct and furnace blower.

Step 3: Check for the filter size indication on the existing filter. If it's not present, use a measuring tape to measure the filter dimensions.

Step 4: Measure the filter length, width, and depth. Note these dimensions down as they will be required to purchase a new filter.

Step 5: Round off the measurements to the nearest inch. For instance, if your filter measures 15.5 inches, round it off to 16 inches.

Step 6: Identify whether your furnace filter is disposable or washable. Disposable filters need replacement once every 1-3 months, while washable filters need cleaning every 3-6 months.

By following these simple steps, you can determine the correct furnace filter size for your heating and cooling system. It's always a good idea to keep extra filters on hand to ensure that you're always ready for a replacement when required.

Different Types of Furnace Filters Available (and Which Size They Require)

When it comes to choosing a furnace filter, there are several options available. Each type has its own benefits and filtration abilities. Here are the most common types:

1. Fiberglass Filter

Fiberglass filters are the most affordable and common type of furnace filter. They are disposable and made of layered fiberglass fibers. They are not as effective in removing smaller particles like pollen or pet dander, but they do a good job at protecting your HVAC system.

The standard size for fiberglass filters is usually 1 inch thick and can be found in sizes of 16x25, 16x20, 20x20, and 14x20.

2. Pleated Filter

Pleated filters are more efficient than fiberglass filters as they are made of pleated, layered fabric that can capture smaller particles. These filters are more expensive than fiberglass filters, but also provide better air quality.

The standard size for pleated filters is usually 1 inch thick and can be found in sizes of 16x25, 20x20, 20x25, and 16x20.

3. Electrostatic Filter

Electrostatic filters use static electricity to capture even the smallest particles, including bacteria and viruses. They are reusable and need to be washed regularly. They are more effective than fiberglass and pleated filters but are also more expensive.

Electrostatic filters come in various sizes and thicknesses, but the most common size is 1 inch thick and sizes of 16x25, 20x20, 20x25, and 16x20.

4. High-Efficiency Particulate Air (HEPA) Filter

HEPA filters are the most powerful type of furnace filter and are capable of capturing up to 99.97% of particles that are 0.3 microns or larger. These filters are usually used in hospitals or laboratories, but also in high-end residential settings. HEPA filters require a special housing and are the most expensive option.

The standard size for HEPA filters is not a specific measurement, as they require a special housing. They can fit various sized openings depending on the housing size.

Now that you know the different types of furnace filters, it's important to choose the right size for your HVAC system. Use the information provided above to find the size that fits your furnace and start breathing cleaner air in your home.

Tips and Tricks for Maintaining Your Furnace Filter

Now that you know the proper size for your furnace filter, it's important to keep it maintained for optimal performance. Here are some tips and tricks to make sure your filter lasts as long as possible:

1. Change your filter regularly: Depending on your filter type and home environment, you should change your filter every one to three months. A dirty filter will block the airflow and reduce your furnace's efficiency.

2. Check your filter's condition: If you notice that your filter is discolored, clogged, or damaged in any way, it's time to replace it. A damaged filter won't be able to properly filter the air in your home.

3. Keep your furnace and filter area clean: Dust and debris can accumulate in and around your furnace and filter area, which can affect the performance of your filter. Regularly clean the area around your furnace and replace any damaged insulation.

4. Choose the right filter material: Depending on your home's needs, you may want to consider a filter with a specialized material such as activated carbon or HEPA. These filters can remove odors, allergens, and other impurities from your home's air.

5. Don't forget about the air intake: Make sure that the air intake area around your filter is unobstructed and free from debris. This will ensure proper airflow and filtration.

By following these simple tips and tricks, you can ensure that your furnace filter is working at its best and keeping your home's air clean and healthy.

The Importance of Regularly Replacing Your Furnace Filter

When it comes to home maintenance, regular furnace filter replacement often falls to the wayside. However, it is a crucial aspect of keeping your home's air quality healthy, preventing furnace malfunctions, and saving on energy costs.

Furnace filters work by capturing dust, dirt, and other airborne contaminants from the air inside your home. Over time, these particles accumulate and can clog the filter, reducing the efficiency of your furnace and decreasing the quality of your indoor air.

By regularly replacing your furnace filter, you can ensure that your furnace is operating at its best efficiency, reducing the risk of costly repairs and prolonging the lifespan of your system. Additionally, regularly replacing your filter can improve the overall air quality of your home, reducing the potential for respiratory issues and allergies.

The frequency with which you should replace your furnace filter depends on several factors, such as the number of people living in your home, the number of pets, and the presence of allergies or respiratory issues. However, a general guideline is to replace your filter every 1-3 months, depending on the type and quality of the filter.

In conclusion, regularly replacing your furnace filter should not be overlooked as it is crucial for maintaining a healthy home environment and preventing costly furnace malfunctions. Remember to check your filter periodically and replace it as needed to keep your home running smoothly and efficiently.


Now that you know the standard sizes for furnace filters and how to choose the right one for your home, you can ensure your HVAC system stays clean and efficient all year round. Remember to check and replace your furnace filter regularly to maintain optimal indoor air quality and energy efficiency. Investing in a high-quality furnace filter is worth it in the long run, as it can improve both your health and your wallet. Don't wait – get started on finding the perfect furnace filter size for your home today!

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.