filterbuy
 

Shop by

Home
>
air filters
>
4 inch
>
20x25x4
>

20x25x4 MERV 8 Pleated Air Filter

 

Actual Size: 19 1/2" x 24 1/2" x 3 5/8"

$99.96$16.66/ea
delivery truckFree Delivery
money downFactory-Direct Low Prices, Made in the USA
editor choiceHassle-Free Returns & Free Exchanges
 
 
 
 
 
 
 
 
 
 
Standard
Standard

RESIDENTIAL AND/OR COMMERCIAL USE

Change Every 3 Months

About

  • This is a list 20x25x4 MERV 8 air filter replacement for your furnace, air conditioner, heat pump, or HVAC system
  • Actual air filter size: 19 1/2" x 24 1/2" x 3 5/8"
  • MERV 8 synthetic media (comparable with MPR 600 & FPR 5) offers standard protection from dust, pollen, and more by trapping 90% of airborne particles without impacting air flow.
  • High-quality construction means electrostatically charged pleated filter media, reinforced wire backing for structural integrity, and a durable frame to resist heat and humidity
  • Built to last 3 months. 300% longer than fiberglass models
  • 100% manufactured in the United States and designed with recyclable materials
  • Learn more about 20x25x4 Air Filters
Quantity

Important Honeywell Size Compatibility Note

If you are replacing a Honeywell 16x25x4 or 20x25x4, your Filterbuy replacement is a 5” filter.
The 5” Filterbuy replacement filter is trimmed down to the “actual” size of your original 4” Honeywell filter.

⚠️ Find your compatible filter by choosing one of the filters below. ⚠️

Honeywell 16x25x5Actual Size: 15.75 x 24.75 x 4.38
Honeywell 20x25x5Actual Size: 19.88 x 24.75 x 4.38

Top-Rated Filters. American Made. Delivered Free.

At Filterbuy, we don't cut corners—we craft high-quality air filters right here in the USA and ship them to your doorstep for free. No delays, no gimmicks—just clean air, made easy. With thousands of five-star reviews and filters built for real life & every HVAC system, it's no wonder why over 4 million families trust Filterbuy.

USA flag flying

Proudly Made In The USA

Two delivery boxes from Filterbuy

Fast, Free Shipping on Every Order

All types of air filters from Filterbuy

Premium Materials That Go The Distance

A child and an adult holding the Filterbuy air filter

85,000+ 5-Star Reviews From Happy Customers

Stacked Filterbuy MERV-8 air filters

Save Up to 70% Per Filter with Packs

Things to Know About Filter Sizes

Finger pointing to nominal size

Nominal Size

  • The rounded size printed on your filter or HVAC unit (e.g., 20x25x4).
  • Usually whole numbers to make identifying and ordering easier.
  • A label for compatibility—not the exact measurement.
Finger pointing to actual size

Actual Size

  • The true, trimmed dimensions of the filter (e.g., 19 1/2" x 24 1/2" x 3 5/8" inches).
  • Filters are manufactured slightly smaller so they slide into the filter slot without forcing.
  • If you don't know your nominal size, measure your filter to get the actual size, then round up to find the nominal size to search on our site.
Help icon

Why the difference?

  • Nominal sizes simplify shopping and standardize categories.
  • Actual sizes ensure the filter fits properly inside your HVAC's filter rack.

How To Find Your Nominal Size When You Don't Know It

Air Filter Explaining Each Size
Nom 20"Act 19 1/2" "
Nom 4"Act 3 5/8"
Nom 25"Act 24 1/2" "
1

Measure length × width × depth with a tape measure to find the actual size.

2

Round up each dimension to the nearest whole number to get the nominal size. Example: 19 1/2" x 24 1/2" x 3 5/8" in → 20x25x4 nominal.

3

Search by nominal size on our site for the best fit.

Help icon
Pro tips: If your filter is missing or damaged, measure the filter slot opening the same way.

Why Getting the Right Size Matters

  • Too small? Air can bypass the filter, reducing air quality and efficiency.
  • Too big? It won't fit—risking bent frames and airflow issues.
  • Just right? You get maximum performance, better filtration, and cleaner air.

Why Choose a 4″ filter

Air Filter 4 inch

4″ filters offer better airflow and a longer life (6–9 months) than standard 1″ or 2″ filters — ideal for homes with pets or allergy concerns.

Sizing note:

  • Requires a 4″ filter cabinet or compatible system.
  • ″4 inch″ is nominal; actual thickness is typically around 3¾″.
Free Exchange Policy

Free Exchange Policy

If the filter you buy doesn't fit, we'll send you a better size.

Need a Non-Standard Size?

Need a Non-Standard Size?

Build a custom filter in just a few clicks.

What's a MERV Rating?

MERV stands for Minimum Efficiency Reporting Value—but don't let the technical name fool you. It's just a way to rate how well an air filter traps stuff like dust, pollen, pet dander, and smoke. The higher the MERV number, the more particles it catches—and the cleaner your air will be.

Swipe To See More
Dust & Debris
Dust Mites & Particles
Pollen
Mold
Lint
Dander
Smoke & Smog
Bacteria
Odors
MERV 8

MERV 8

Comparable to:FPR: 4-7MPR: 600-1000



MERV 11

MERV 11

Comparable to:FPR: 6-9MPR: 1200-1550


MERV 13

MERV 13

Comparable to:FPR: 10MPR: 1900-2800

What Makes Our Filters Last 90 Days? Quality, From the Inside Out

We build every Filterbuy filter to deliver reliable 90-day performance—thanks to smart design and premium materials that do the heavy lifting. Here's what makes the difference:

Pleated Design

More pleats = more surface area to capture dust and debris, keeping your air cleaner longer.

Electrostatically Charged Media

Pleats are magnetized to attract and trap microscopic particles—like pet dander, pollen, and smoke.

Synthetic Beverage Board Frame

Engineered to resist warping in extreme temperatures and high humidity.

Air Filter Wit Zoom In Key Features

Aluminum Dual Wire Backing

A layer of metal reinforcement keeps pleats evenly spaced and structurally sound—no sagging, even at high airflow.

Made in the USA

Assembled with care. Built to perform. Ships fast, free, and reliably from our U.S. facilities.

How to Install Your Filter in 4 Simple Steps

How to install your filter - Step 1 - Return Vent

Turn Off Your HVAC SystemSafety first.

How to install your filter - Step 2 - Filter Housing

Remove The Old FilterLook for the airflow arrow and make note of the direction.

How to install your filter - Step 3 - Filter Housing

Slide In Your New FilterArrow should point toward the system (same direction as before).

How to install your filter - Step 4 - Filter Housing

Turn Your System Back OnAnd enjoy the fresh, clean air.

Auto Delivery Filterbuy

Never forget to replace your air filter again.

  • Save 5% on every order
  • Choose Your Delivery Schedule
  • Edit, Skip, or Cancel Anytime.
Learn More

Pleated Filters vs. Fiberglass—What's the Difference?

Not all air filters are created equal. Pleated filters don't just last longer—they actually clean your air better. Here's how they stack up:

Pleated Filter

Pleated Filters

Efficiency:

High (MERV 8–13) – Traps more particles

Lifespan:

90 days – Long-lasting performance

Air Quality:

Excellent – Cleaner, healthier air

Materials:

Recyclable and durable

Fiberglass Filter

Fiberglass Filters

Efficiency:

Low (MERV 4 or less) – Misses small stuff

Lifespan:

30 days or less – Replace often

Air Quality:

Minimal – Basic protection only

Materials:

Thin, flimsy, and not recyclable

Pleated filters are a no-brainer—more protection, less hassle, and better air for your home.

How Often Should You Change Your Filter?

Changing your filter on time keeps your HVAC system running efficiently—and helps protect your lungs from dust, allergens, and airborne irritants. Here's how often to swap it out based on your needs:

Calendar Illustration Every 90 days

Every 90 Days

Standard Schedule

For most homes without pets or special air quality concerns. Great for general upkeep and energy efficiency.

Calendar Illustration Every 60 days

Every 60 Days

If You Have Pets or Allergies

Shedding fur, dander, and allergy triggers can build up fast. Changing your filter every two months helps keep the air fresher and symptoms at bay.

Calendar Illustration Every 30 days

Every 30 Days

If You Have Respiratory Concerns or Live in Smog/Wildfire Zones

For households affected by smoke, pollution, or respiratory conditions, monthly changes ensure maximum protection.

Help icon
Final tip:
Want to stay on track? Set a reminder—or skip the stress with auto-delivery so fresh filters show up right when you need them.

Don't Just Take Our Word For It...

Got More Questions? We've Got Answers.

























Product Specifications

Nominal Size20 x 25 x 4 inches
Actual Size19 1/2" x 24 1/2" x 3 5/8" inches
Filter TypePleated
MediaElectrostatically Charged
FrameBeverage Board
MERV Ratings Available8, 11, 13
LifespanUp to 12 Months
OriginMade in USA

Why Choose Filterbuy 20x25x4 MERV 8 Pleated Air Filter

Think of Filterbuy 20x25x4 MERV 8 Pleated Air Filter as a top goalie for your home's air. It catches harmful particles while keeping airflow smooth and efficient.

Size matters with air filters. Bigger filters capture more pollutants and are built with moisture-resistant materials to last in any condition.

Key Takeaways

MERV 8 Rating Efficiency

Better air helps prevent health issues like allergies and breathing problems. A MERV 8 filter works well for homes and businesses. They trap 90% of airborne particles.

Filterbuy 20x25x4 air filter MERV 8 strikes a balance between good particle filtration and low airflow resistance. This keeps your HVAC running smoothly while improving air quality. Understanding this helps you choose the right filter.

The Pleated Design Advantage

The design of this Filterbuy product improves airflow and overall performance, setting it apart from the rest. Our pleated air filters are at least 20 times more efficient than standard fiberglass filters at capturing dust, allergens, and bacteria.

This design increases the filter’s surface area, allowing it to trap more particles without blocking airflow. It's like giving the filter extra reach to catch more pollutants.

Filterbuy MERV 8 pleated air filter 20x25x4 helps capture particles while allowing air to flow smoothly, keeping indoor air clean and reducing strain on your equipment.

Benefits of High Quality Filters

Top air filters from Filterbuy improve health and indoor air quality. While ensuring efficiency for a healthier environment.

Image of MERV 8 air filters for improved indoor air quality and a healthier home environment.

Longevity and Durability Explained

This filter provides long-lasting durability, ensuring better HVAC performance without sacrificing air quality.

Made from synthetic electrostatic media that resist moisture and microbes. This advanced material is significantly more efficient at capturing particles compared to basic cotton media used in other filters.

The filter maintains its strength in different environments, effectively removing pollutants in both humid and dry conditions.

Why choose Filterbuy? 

Here are the following aspects that set Filterbuy air filters apart from competitors.

Frequently Ask Questions

What is a MERV 8 filter good for?

One of the primary benefits lies in their ability to control dust levels. They trap common airborne particles, including dust mites, mold spores and pollen. They improve indoor air quality and provide a healthier living environment. Another advantage is their energy efficiency.

How long does a 20x25x4 air filter last?

It has a lifespan of around three to six months. Depending on the quality and the environment. However, factors such as the number of residents, the presence of pets and the level of air pollution affect its lifespan.

Are higher MERV filters worth it?

Higher MERV benefits include enhanced filtration capabilities, resulting in improved indoor air quality by effectively capturing smaller particles, including dust, pollen and other allergens. This can be particularly beneficial for households with individuals who suffer from allergies, asthma or other respiratory conditions.

Does a MERV 8 filter restrict airflow?

In consideration of airflow restriction, this equipment presents a balanced solution. Their design effectively captures particles without significantly compromising air circulation. Its efficiency is a testament to its superior engineering, which manages to provide adequate filtration while ensuring minimal airflow impact.

What MERV rating is best for airflow?

The best one for airflow depends on the specific requirements of your system. And the quality of air you desire in your environment. Consulting with a professional is crucial when selecting the most suitable level for your needs.

Is MERV 14 too high for residential?

They remove extremely small particles such as bacteria and tobacco smoke. While this level of filtration may be desirable in specific scenarios, for example, in homes with individuals suffering from severe allergies or respiratory conditions, it may not be necessary in a typical residence.

Do more expensive air filters make a difference?

Balancing cost against performance when selecting one raises important considerations. An effective cost analysis should compare not only the upfront price but also the ongoing maintenance costs and the lifespan. Similarly, a comprehensive performance evaluation must consider its ability to improve air quality by removing particles and reducing allergens.

How often should I change my MERV filter?

Maintenance schedule is every 60 to 90 days. This varies based on several factors. For example, homes with pets or occupants with allergies may require more frequent changes, perhaps every 30 to 45 days, due to the higher amount of airborne particulates.

Which filter is better HEPA or MERV?

Both have comparable lifespans but ongoing maintenance and environmental impact may vary. HEPA often requires professional installation and disposal while MERV, especially lower-rated ones, are user-friendly and more environmentally sustainable due to less frequent changes.

Can I use a 20x25x4 instead of a 20x25x5 filter?

Keep in mind that the size should match the specifications of your system. Using one that is too big or too small causes the system to work harder. This leads to decreased efficiency and possible damage over time.

Which type of air filter will last the longest?

Regardless of type, the longevity extends with proper maintenance. Regular inspection, timely replacement or cleaning, and ensuring a good fit can all prolong the lifespan. However, remember that maintenance tips should be followed as per the manufacturer's specifications to maintain optimum performance.

How often do you need to clean a permanent air filter?

This equipment requires a particular cleaning schedule. It is recommended to clean them at least every 30 to 60 days. Depending on usage and indoor air quality. The cleaning methods usually involve vacuuming to remove the accumulated dust and debris, then washing it with warm water and mild detergent.