How do you measure an air filter?

An air filter’s size is described using three different measurements. The length, width, and depth of a filter are printed out in small numbers along the cardboard edge of a Filter King brand filter. But other filters may not have this information conveniently located, and you may need to find the measurements yourself. When doing so, check to see whether the filter is square or not. If it is not square, then the smallest-size side’s measurement goes first, followed by the next side, and then finally the depth measurement. 10x15x1 is a proper example of a correct size. Be sure to round the measurements up when you order new air filters. This rounded measurement is referred to as the nominal size and is used to match the right filter to its fitting air filter slot. By using the nominal size, you can order a new air filter that slides in and out of place with ease.

What is the most common size furnace filter?

Currently, the most common size furnace filters are 10x20.

What size do furnace filters come in?

There are hundreds of variant sizes of furnace filters because air filters and furnace are both the same. The only difference between the two is location. Filter King offers hundreds of different filter sizes capable of use for several home systems, including your furnace.

Where is the air filter on an AC unit?

Depending on your AC unit, the air filter slot may be located in a hard to find location. First, try checking the blower compartment or return air duct where the air is cleaned before going through the unit. The unit itself may have the air filter inserted in a specific location.

Are air filters important?

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 making sure that any air brought in is cleaned before entering the system. Without filtration, the air coming in from outside may contain any number of dust, debris pollutants, and allergens.

What are the symptoms of a bad air filter?

When an air filter is bad, that can mean that it is either dirty or broken. When dirty, the symptoms include the air inside of a home drying out or stagnating and dust particles filling the air. If the air filter is broken or not working, the symptoms include any number of particles such as pollen, dust, mold, dust mites, bacteria, pet dander, smoke, and viruses.

How much is an air filter for House?

The price of a single Filter King brand air filter varies depending on its measurements. However, the price falls when you buy multiple filters per order. Orders of two or more filters are also shipped for free.

How many air filters does a house have?

This is entirely dependant on your home and the kind of AC system it has. Consult the owner’s guide for your home air system to understand how many air filters your home has and in what sizes.

What does MERV 8 protect against?

In short, MERV 8 blocks particles of 3 microns and larger. These includes: Dust Pollen Dust mites Bacteria Pet Dander (unless you have more than one pet) Cigarette smoke, smog, and general allergens would best be handled by MERV 11. While, if bacteria, mold spores, and even wood-burning fireplaces are a concern, then you’d need to look at MERV 13.

MERV 8

Shop MERV 8 Air Filter & Furnace Filters

Q: Who is the MERV 8 best for?

MERV 8 is the minimum standard air filter we recommend for residential use. That said, to understand the MERV 8, it’s best to look at what it doesn't protect against. If you have allergies or multiple pets, or other chronic breathing problems, you’ll be best served by going up to MERV 11 or MERV 13. Or, if you are a smoker (or live with one), or if you live in a city that has smog, you should consider a higher rating, as well. As you can see, much of which filter you need depends on your lifestyle and what kind of air you regularly come into contact with — or what breathing issues you regularly battle.

MERV 8 air filters are the most common on the market, offering up to 90% efficiency in capturing common airborne particles like dust, pollen, dust mites, and pet dander (ideal for homes with one pet).

These filters are suitable for residential homes, commercial buildings, industrial workplaces, and paint booths. They meet the minimum recommended standard for residential use and help maintain cleaner, healthier indoor air.

Which MERV 8 Air Filter Do You Need?

What Does the MERV 8 Filter Protect Against?

MERV 8 furnace and air filters effectively block airborne particles measuring 3 microns or larger. This filtration level provides essential protection and helps maintain a healthier indoor environment.

Specifically, MERV 8 filters help capture:

Dust: Common household dust can trigger allergies and negatively impact indoor air quality. MERV 8 filters effectively trap dust particles, reducing their circulation.
Pollen: Especially beneficial during allergy season, these filters reduce pollen levels indoors, minimizing allergy symptoms like sneezing, itchy eyes, and congestion.
Dust mites: MERV 8 filters significantly reduce dust mites, microscopic creatures that commonly cause allergic reactions and respiratory discomfort.
Bacteria: These filters effectively trap larger bacterial particles, helping to maintain cleaner air and reducing exposure to airborne pathogens.
Pet Dander: MERV 8 filters efficiently capture pet dander, reducing allergens, although households with multiple pets may benefit from upgrading to a higher MERV rating.

Available Air Filter Sizes and Types

Most Common MERV 8 Filters

Below are the most common MERV 8 filter sizes, perfect for residential and commercial HVAC systems.

Popular MERV 8 Filter Sizes

MERV Comparison

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Recommended for

Ideal for

Comparable Ratings

Particle Capture

Dust / Pollen

Mold

Dust Mites

Bacteria

Pet Dander

Smoke

Allergens

Cooking

Odor

Smog

MERV 8

General Use

Families & Offices

Similar to MPR 600 & FPR 5

Filters 90% of Common Particles

Yes

MERV 11

Enhanced Filtration

Allergy Relief

Similar to MPR 1000–1200 & FPR 7

Filters 95% of Common Particles

Yes

MERV 13

Highest Efficiency

Sensitive Environments

Similar to MPR 1500–1900 & FPR 10

Filters 98% of Common Particles

Yes

MERV 8 Carbon

Odor Control & General Use

Homes with Pets, Smokers, or Odors

Not specified

Filters 75–80% of particles 1–3 microns

Yes

Who Is the MERV 8 Best For?

MERV 8 filters are best if you're looking for standard protection in typical residential environments. They effectively handle common household particles like dust, lint, pollen, and mold spores.

MERV 8 Carbon filters offer the same solid particle protection as regular MERV 8 filters but with an added odor control layer. Thanks to their activated carbon layer, they’re ideal for homes with pets, smokers, or mild cooking odors—anywhere you want to reduce unwanted smells without upgrading to a higher filtration level.

If you're looking for the best protection against cigarette smoke, smog, and general allergens, MERV 11 is the better option. And if germs, mold spores, or even wood-burning fireplaces are a concern, go with MERV 13 for maximum efficiency and air purity.

Ready to choose the right filter for your needs? Browse all filter sizes here.

Frequently Asked Questions

Is a MERV rating of 8 good?

Yes, a MERV 8 rating is considered good for standard residential and commercial HVAC systems. It effectively captures common airborne particles such as dust, lint, pollen, and mold spores, improving indoor air quality for most households.

Is MERV 8 too restrictive?

No, MERV 8 filters are specifically designed to provide a balance between filtration efficiency and airflow. They're not typically restrictive and are safe for standard residential HVAC systems without significantly impacting system performance.

Is MERV 8 or MERV 11 better?

MERV 11 filters offer higher filtration efficiency than MERV 8 filters, capturing smaller particles such as smoke, smog, and allergens.

If you have allergies, more than one pet, or sensitivities to pollutants, a MERV 11 filter would be more effective. A MERV 8 filter is usually sufficient for general use without special sensitivities.

How often should a MERV 8 filter be replaced?

It's recommended that MERV 8 filters be replaced every 3 months. However, if you have multiple pets, allergies, or if your home sees high traffic or dust, consider replacing them every 1-2 months for optimal indoor air quality.