Collection: Aerostar

Aerostar Furnace and AC Air Filters by Size and MERV Rating

This page collects Aerostar pleated air filters for furnaces, central air conditioning and HVAC systems. The listings cover 18 sizes, almost all 1-inch filters plus a 4-inch 20x25x4, in MERV 6, 8, 11 and 13, sold in multi-packs. Start by reading the size printed on the edge of your current filter, then pick the MERV rating your system calls for.

Find Your Aerostar Filter Size

Each size links to a listing. The MERV ratings and pack sizes below are what is offered across the Aerostar listings for that size, so open the link and check the options on the product page.

Nominal Size Versus Actual Size

The size on the filter frame, such as 20x25x1, is the nominal size. The actual dimensions are usually a little smaller, and Aerostar listings give the actual size, for example 17.50 x 19.50 x 0.75 inches for the 18x20x1. Match the nominal size printed on your old filter, and use the actual size on the product page to double-check the fit.

Choosing a MERV Rating

MERV measures how well a filter captures particles, on a scale where a higher number captures smaller particles. MERV 6 and 8 are basic dust and lint filters, MERV 11 adds finer capture for pollen and pet dander, and MERV 13 targets even smaller particles. Higher-rated filters also add airflow resistance, so check your furnace or air handler manual for the highest rating it recommends before moving up.

How Often to Replace an Aerostar Filter

A common guideline is to replace 1-inch filters every one to three months and thicker 4-inch filters less often, but the right interval depends on your system, pets, dust and how much you run it. Check the filter monthly and replace it when it looks gray and loaded, and follow your equipment manufacturer's guidance.

Our Fit Guarantee and Shipping

US orders ship free. If a filter listed as compatible with your system does not fit, our Fit Guarantee covers it within 30 days of delivery. See the full air filter range for other brands and sizes.

Aerostar Filter Questions

How do I find my air filter size?

Look at the edge of your current filter, where the nominal size is printed, such as 16x25x1. If there is no printed size, measure the length, width and thickness and round to the nearest nominal size.

What is the difference between MERV 8, 11 and 13?

Higher MERV numbers capture smaller particles but restrict airflow more. Check your system manual for the highest rating it supports.

Can I use a 4-inch filter in a 1-inch slot?

No. Filters only fit the slot depth they were made for, so match the thickness as well as the length and width.

Do these come in multi-packs?

Yes. The listings are sold in multi-packs, commonly 4 or 6, and some sizes also come in 2 or 12. Check the pack size on each product page.