Home Air Filters & HVAC Filter Replacement: Any Size You Need

Looking for the perfect air filter replacement?

We make finding the right HVAC filter simple. Browse our standard air conditioner filters by selecting your dimensions, or get a precision-cut custom size to match your exact specifications. Order a Custom Air Filter.

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Didn't find the right size? We can make you a custom-sized air filter.

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Shop By MERV Rating

  • Standard Protection
    For Basic Dust and Debris

    MERV 8

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    Ideal for general residential use, MERV 8 filters provide standard filtration for everyday air quality needs. They capture larger airborne particles like dust, lint, and pollen, perfect for households without pets or respiratory sensitivities. They’re a solid choice for basic HVAC system protection without restricting airflow.

    Shop MERV 8
  • MERV 11

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    Our most popular filter strikes the right balance between airflow and particle capture. MERV 11 filters trap finer allergens like pet dander, dust mites, and mold spores. They’re great for homes with pets, allergy concerns, or anyone looking to improve indoor air quality without upgrading HVAC systems.

    Shop MERV 11
  • MERV 13

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    For the highest level of protection, MERV 13 filters block microscopic particles, including smoke, bacteria, and virus-carrying droplets. They’re recommended for people with asthma or severe allergies and ideal for medical offices, commercial spaces, or homes where maximum filtration matters most.

    Shop MERV 13

Not Sure What HVAC Filter Replacement You Need?

We've got you covered. At Filter King, we specialize in helping you find the exact AC or furnace filter you need, whether it's a common size or a custom fit.

Find Your Filter Here

Why Choose Filter King?

Trusted by homeowners and businesses alike, Filter King is the go-to provider for high-quality air filters in any size. From custom-built solutions to fast, reliable shipping, we make it easy to get the exact HVAC filter you need, delivered right to your door.

Air & Furnace Filter Deliveries to Anywhere in the USA

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Free & Fast Shipping

You're busy; we get it. That's why we offer free 2–5 day shipping on all orders, with reliable delivery straight to your doorstep. Get the filters you need, when you need them, without the hassle.

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We hate fine print as much as you do. No contracts or commitments! Pause, change, or cancel your delivery service whenever you need to.

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Made in the USA

Not only are all our filters proudly manufactured and assembled here in the USA, but they also comply with all FTC rules and are certified by regulatory bodies such as SafeHome™.

Custom Air Filter Sizes

Custom Sizes Available

Need an uncommon filter size? We specialize in made-to-order air filters built to your exact dimensions. Whether it's for a unique home setup or a specific HVAC system, we’ll get it right.
Order Custom Air Filters

Bulk & Wholesale Ordering

Bulk & Wholesale Ordering

Managing multiple units or commercial properties? We offer volume pricing and fast, reliable delivery tailored to the needs of property managers, contractors, and facility teams.
Shop Bulk Air Filters

With the right air filters, you can protect your loved ones from harmful airborne allergens and irritants such as:

Filter Features

Air Filter FAQs

Most homeowners should replace their furnace filter every 90 days. However, your actual replacement schedule can vary depending on your lifestyle and air quality needs.

If you have pets, smoke indoors, or run your HVAC system frequently, changing your air filter every 60 days is a good idea.

For households dealing with allergies or asthma, replacing your HVAC filter every 30 days, especially with a higher MERV rating, can help keep the air cleaner and healthier. Regular air filter replacement also improves system performance and energy efficiency.

To replace your furnace filter, first locate the return air vent. It’s usually found on an interior wall or ceiling and may be painted to match the surrounding surface. Open the vent by pulling the small lever or latch on the side. Remove the old HVAC filter and slide in your new one, ensuring the airflow arrows on the filter match the airflow direction in your system.

A proper air filter replacement helps your furnace or air conditioner run more efficiently and keeps your indoor air cleaner.

The right time for a furnace filter replacement depends on your indoor air quality goals. Filter King filters are designed to last up to 90 days, but many households benefit from more frequent changes.

If you have pets, smoke indoors, or live with allergies or asthma, replacing your HVAC filter every 30 to 60 days can help improve air quality and keep your system running efficiently. A fresh air filter ensures cleaner air and better heating and cooling system performance.

The location of your air filter depends on your HVAC system setup. Most commonly, the air filter is found in the return air duct or inside the blower compartment, where air enters the system to be cleaned.

Some air conditioner filters are placed directly inside the unit, while others sit behind a wall or ceiling vent. If you're unsure, check your system manual or contact Filter King for help identifying the right air filter replacement location for your setup.

Technically, your furnace or air conditioner can run without a filter, but it’s strongly discouraged.

The air filter acts as a barrier that protects your HVAC system from dust, dirt, and debris. Without it, particles can build up inside the system, reducing efficiency and leading to costly damage over time.

A proper HVAC filter replacement helps maintain clean airflow, protects your equipment, and supports healthier indoor air quality.

Installing your air filter backward can reduce airflow and strain your HVAC system. Filters are designed with a specific direction. The porous side allows air flow, while the denser mesh side captures particles.

When reversed, the filter resists airflow, forcing your system to work harder. This can lead to higher energy bills, reduced air quality, and long-term mechanical damage. Always check the airflow arrows on the filter before installation to ensure proper furnace filter replacement.

Yes, a dirty air filter can significantly reduce your air conditioner's efficiency. As dust and debris build up, airflow becomes restricted, forcing your HVAC system to work harder to cool your home.

This can lead to poor cooling performance, increased energy bills, and added strain on your equipment. How long an air filter lasts depends on your home's size, daily usage, and the filter's MERV rating. Regular air filter replacement is essential for better performance and air quality.

A dirty furnace filter blocks airflow, forcing your HVAC system to work harder just to circulate air. As the filter becomes clogged with dust and debris, it restricts clean air from moving through your system, which can reduce efficiency and increase energy costs. Over time, this can also lead to poor indoor air quality, with stale or dusty air lingering in your home. Regular HVAC filter replacement helps maintain airflow, protect your system, and keep your home’s air fresh.

Yes, they are very important to any air system they are in. Air systems have no way of knowing whether the air they are bringing in is clean or dirty. Air filters are essential to ensuring that any air brought in is cleaned before entering your living space. Without filtration, the air coming in from outside may contain any number of dust, debris, pollutants, and allergens.

Air Filter Basics

What Are HVAC Filters?

HVAC is an acronym for "heating, ventilation, and air conditioning."

An HVAC is a system that provides both heating and cooling to residential and commercial buildings. The ventilation function in an HVAC system uses a furnace filter to clean the indoor air and replace it with fresh air from the outdoors; this removes anything in the air, ranging from smoke, dust, moisture, and undetectable gases that decrease ambient air quality.
Learn more about HVAC

What Is MERV Rating?

MERV stands for Minimum Efficiency Reporting Value. In short, a MERV rating lets you know what air particle size an air filter will trap. A higher rating means that the filter can trap smaller air particles.
Learn more about MERV ratings

Dirty-Clean Filter

Breathe Easier with Cleaner Air: Trusted AC and Furnace Filters That Work

Roughly one in seven Americans lives with respiratory issues like asthma or COPD. Using high-quality AC and furnace filters is a simple way to create a healthier home environment and protect the people you care about most.

Breathe easier knowing Filter King has your air covered.

Don’t Take It From Us...Our Customers Say It Best

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Don M.
Verified Buyer
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04/30/2025

20x25x1 filter

Very nice looking filter. works great with my A/C unit. Very attentive email support. I made an error in the size and they sent me another immediately. Thank you Filter King

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Manny F.
Verified Buyer
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04/17/2025

Great custom-fit filter!

These custom-order filters sit perfectly in an uncommon-sized filter housing. No more air leaks and no more cutting generic, fiber weave filters to fit in the housing.

R
Ryan K.
Verified Buyer
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04/14/2025

Never buy anywhere else

The company has always been great. I get my filters for my 2 purifiers through here custom cut. Pennies on the dollar vs buying the brand name. We have been buying here for several years and have never been disappointed. The customer service is also the beat around.

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Judy T.
Verified Buyer
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04/11/2025

Thank you!

We have an odd size filter and had to order customs. They fit perfectly. We’ve noted a significant reduction in dust and noise since changing from the washable/reusable filter, too!

Shop By MERV Quality to Shop By MERV Rating

Filter King makes a variety of MERV-rated standard filters for all commercial and residential HVAC systems, and we can also manufacture custom-sized filters on request.

merv-8

Good: MERV 8 Filter

At a minimum, MERV 8 filter can be appropriate for most residential homes. It can block up to 90% of airborne contaminants such as dust, mold, and pollen. Recommended for use in basic and standard homes and businesses.

merv-11

Better: MERV 11 Filter

MERV 11 filter is a mid-level filter, a step higher than MERV 8, and can remove a much higher percentage of contaminants including pet dander and allergens. Its recommended for homes with pets and people with mild allergies or anyone looking for further filtration.

merv-13

Best: MERV 13 Filter

In addition to filtering everything that MERV 11 filter can, MERV 13 air filter can filter out smoke, smog, and virus carriers. MERV 13 provides the highest level of filtration and is suitable for homes with people that smoke, have severe allergies, asthma, and other respiratory issues.

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Customers who join us today for our air filter delivery subscription service will receive $5 off their first and ongoing orders.