• No minimums, no surprises — we ship every order for free! We'll get your filters out the door fast so you can enjoy clean air and water without paying extra.

  • Shop with confidence! If you're not completely satisfied with your purchase, you have up to one year to return it for a refund or exchange. We stand behind every filter we sell.

    Learn More

  • Every order is carefully packed and shipped by our team in Indiana. Your purchase helps support American jobs and hardworking families right here in the Midwest. Our AIRx Furnace / AC Filters and ClearChoice Fridge Filters are made in the USA.

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  • No minimums, no surprises — we ship every order for free! We'll get your filters out the door fast so you can enjoy clean air and water without paying extra.

  • Shop with confidence! If you're not completely satisfied with your purchase, you have up to one year to return it for a refund or exchange. We stand behind every filter we sell.

    Learn More

  • Every order is carefully packed and shipped by our team in Indiana. Your purchase helps support American jobs and hardworking families right here in the Midwest. Our AIRx Furnace / AC Filters and ClearChoice Fridge Filters are made in the USA.

Cart 0

We don't know what's in your water,
but we know there's nothing in your cart.

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21x21x5 Filters



What Our Customers Have to Say

Cheryl A. 1 day ago
5
June 2026 was our fourth or fifth purchase from Discount Filters. The AC filters we've purchased are reasonably priced as well as having an advertised discount (email). Shipping has been excellent and on time. We will continue using them for our filter needs.
Samantha W. 1 day ago
5
Grateful I found this size at Discount Filters and at a resonably good price. Much better than ordering on Amazon. Shipped quickly.
Catherine B. 5 days ago
5
I'm very happy with the product and the fact that you carry our size of 16x25x3. This appears to be a rare size and not available to buy in any local stores (trust me, I looked!). I'm bummed I passed on the Memorial Day sale since it was the best price, but I'm still happy with the coupon code provided and will continue to order my filters thru you. Thank you!
Linda E. 6 days ago
5
Even though they initially cost more than the filters you change monthly, I think they are superior by far. I change them twice a year, and my house seems noticeably cleaner with less dust. Great product for my type of furnace!