About Air Filter Sizes

A simple, free tool to help you find the right furnace or AC filter size.

Buying a replacement air filter should be easy, but it often isn't. The size on the label doesn't match the measurements, there are dozens of sizes, and MERV ratings can be confusing. Air Filter Sizes exists to make that one small chore quicker.

What you'll find here

• A size lookup that explains nominal vs. actual size.
• A plain-English way to choose between MERV 8, 11, and 13.
• Short guides on finding your size, common sizes, and how often to change your filter.

How we write our guides

We stick to general, widely accepted guidance and keep it conservative. We're not HVAC technicians, and nothing here replaces your equipment manual, your filter's packaging, or advice from a licensed professional who has seen your system.

How the site is funded

The site is free to use. Some product links may become affiliate links, which means we may earn a commission at no extra cost to you. See our affiliate disclosure for details.

Contact

Email us at info@airfiltersizes.com.