Is Filtrete on Sale? November 2026

Questions and answers

What does the MPR number on a Filtrete filter mean?

MPR stands for Microparticle Performance Rating, 3M's scale for capturing particles between 0.3 and 1 micron. Higher numbers mean finer capture; Allergen Defense sits in the low-to-mid range and Ultra Allergen higher up. MPR is not the same as MERV, the HVAC industry rating.

Which Filtrete filter should I pick, Ultra Allergen or Allergen Defense?

Choose Ultra Allergen if you have allergy sufferers, pets or a smoky environment and your system handles a denser filter. Allergen Defense is the general-purpose choice for dust and pollen and puts less strain on airflow. Check your furnace's maximum rated MERV before moving up.

Do these filters fit standard furnace and AC slots?

Both come in common nominal sizes such as 16x25x1 and 20x25x1, and Filtrete lists actual dimensions on the box because nominal sizes run slightly large. Measure the slot, not the old filter's label, before ordering. Depth matters too: a 1-inch slot will not take a 4-inch media filter.

How often should a Filtrete filter be changed?

3M advises every 90 days for the thicker high-MPR filters, and more often with pets, construction dust or heavy runtime. A filter that looks gray across the pleats is loaded even if the calendar says otherwise. Restricted airflow raises energy use and can ice the coil.

What warranty comes with Filtrete filters?

3M covers Filtrete HVAC filters against manufacturing defects, and claims go through 3M with proof of purchase. The warranty does not cover normal loading, improper sizing or damage from a system running with blocked airflow. Keep the packaging until the filter is installed.

Are there Filtrete discount codes?

Deal.ai checks what Filtrete products actually cost at every store, so a real markdown shows on this page as a deal as soon as it starts, and each product's page has its price history to tell a sale from its usual price.