MadMax Trade Supply
A stack of plain white pleated furnace air filters standing on a utility-room floor beside a furnace.

HVAC Air Filters

Replacement furnace and air-conditioner filters listed by nominal size (width x height x depth, in inches) and MERV rating. Nominal size is the rounded size printed on the filter frame; actual size is usually slightly smaller. Check the size printed on your current filter before ordering.

Available to order

Prices include sales tax (see terms). Items marked "Shipping calculated before payment link" have shipping calculated and shown in your payment link before you pay. Typical delivery is a few business days in the contiguous United States. A delivery estimate is confirmed in your payment-link email. Shipping to Alaska, Hawaii, Puerto Rico, other US territories and APO/FPO addresses is not included in any price; we quote it in your payment-link email before you pay. Images are representative; tap a picture to enlarge it.

Don't see your exact item? Email us the part number or size: tamara@madmaxsupply.com

Attributes we list for each item: Nominal size (in), Depth (in), MERV rating, Pack size.

Fix-it guides

Buying guides

Shop by filter size

Indexable size pages for the nominal sizes in our catalog.

What size furnace filter do I need?

FAQ

How do I find my air filter size?

Read the size printed on the cardboard frame of your current filter, for example 16x25x1. Use that nominal size in the lookup.

Which MERV rating should I pick?

Use the rating your HVAC equipment maker or contractor recommends. Higher MERV filters capture smaller particles but can restrict airflow on some systems.

How often should I replace it?

Follow your equipment manufacturer's guidance. Many 1-inch filters are changed every 1–3 months; thicker media filters last longer.