Air & Furnace Filters Size Chart

What Size Air Filter Replacement for My Furnace Should I Buy?

Regardless of the air or furnace filter size you need, we have it in stock and ready to ship. Use the size selector to enter your filter's dimensions: width (long side), depth (short side), and thickness. You can also scroll down and use the Air Filter Sizes chart to pick the right size and quickly check out.

Filter Size

Available Air Filter Sizes and Types

Can't find your size? Click here for Custom Air Filters

What Are the Most Common Furnace Filter Sizes?

Currently, the most common size furnace filters are:

USA All Air & AC Filter Sizes are Proudly Made in the USA

Filter King is a US-based manufacturer, and all our materials are produced and put together in our Alabama warehouse right here in the USA.

Money back guarantee 30-Day Money-Back Guarantee

Because we're confident of our high-quality premium filters, we offer a 30-day money-back guarantee on any furnace filter size. If you're unhappy with your purchase, reach out to us within 30 days and we'll gladly refund you.

Oh, and we offer free shipping when you order two or more filter packs.

USA Subscribe and Save: Buy More, Pay Less

Why go through the trouble of buying replacement filters every month when you can get us to do it for you? Our simple and scheduled AC and furnace filter delivery service is exactly what you need.

Swap your AC/furnace filter on time, every time! We have a wide variety of sizes to meet your every need.

Questions about air and HVAC filter sizes?

There are hundreds of variant sizes of air and furnace filters because they 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.

Air filters are sized using three measurements: length, width, and depth. On Filter King brand filters, these numbers are printed on the cardboard edge of the frame. Other brands might not show this clearly, so you might have to measure your filter yourself.

When measuring, first check if the filter is square. If it’s not square, start with the smallest side, then the next larger side, and finally the depth (thickness). For example, a correct size is listed as 10x15x1.

Always round your actual measurements up to the nearest whole number—this is called the filter’s nominal size. The nominal size helps you easily find a replacement that fits smoothly into your air filter slot.

Replace furnace filters every 1–3 months, depending on the type of filter, household conditions, and if pets or allergies are present. Checking your filters monthly is recommended to maintain optimal air quality.

Expensive filters generally offer higher efficiency and capture small particles like allergens and bacteria. However, affordable filters still effectively trap common dust and debris, making them suitable for basic home air quality.

Check your existing filter's nominal size (printed on the frame) or measure it yourself, rounding up to the nearest whole number. Also, choose a MERV rating suitable for your needs—typically, MERV 8 is ideal for standard residential use.