Fits checked Oct 1, 2026 · How we check
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AprilAire · media air cleaner · media air cleaner cabinet

AprilAire U131 replacement filter

Use part UK311, or any one of UK313. Lasts up to 12 months.

Any one of these fits · standard choice

Maker lists this model

AprilAire UK311 MERV 11 + rails

AprilAire UK311 (Replaces 310) MERV 11 TriPure Filter + Upgrade Rails

Part number
UK311
How many
1 per unitpacks: UK311 02 (2)
How often
Lasts up to 12 months
Size
20 x 20 x 4 in20 x 20 x 4 in nominal (20.61 x 21.75 x 3.68 actual)

AprilAire lists the U131 on the UK311 page (MERV 11); the UK311 bundles one-time upgrade rails that older cabinets need, and the filter-only refill is the 3F311.

Buy UK311 MERV 11 + rails on AmazonManufacturer page

Opens an Amazon search for AprilAire UK311 MERV 11 + rails. Check the listing says UK311.

See the sources

Compare the 2 options

The U131 holds one filter at a time. Any one of these fits; AprilAire ships it with the first one.

FilterGradeSizeHow oftenBuy
UK311 MERV 11 + railsUK311standard choiceMERV 11 TriPure 3-inch filter, one-time upgrade rails20 x 20 x 4 inLasts up to 12 monthsAmazon
UK313 MERV 13 + railsUK313MERV 13 TriPure 3-inch filter, one-time upgrade rails20 x 20 x 4 inLasts up to 12 monthsAmazon

Other genuine options from AprilAire

Variants and kits the maker sells for this model. Same fit, different media or packaging.

  • 3F311 filter only (ships in the U131; AprilAire's subscription refill)
    3F311 · Find on Amazon

Sources

High confidence: the manufacturer names this exact model on a live page. Each line is the page we read and the day we read it.

  • Which filter fits shop.aprilaire.com Maker's own page checked Oct 1, 2026
    Compatible Models: 1310, 2310, 3310, 4300, U131, U233
  • How many shop.aprilaire.com Maker's own page checked Oct 1, 2026
    INCLUDED IN THE BOX: (1) U131 Air Purifier (1) 3F311 Air Filter; Filter Nominal Dimensions (H x W): 20 x 20 (inches)
  • How often shop.aprilaire.com Maker's own page checked Oct 1, 2026
    LONG FILTER LIFE – One filter lasts up to 12 months
  • Size shop.aprilaire.com Maker's own page checked Oct 1, 2026
    Nominal Measurements: 20H x 20W x 4D (inches) Actual Measurements: 20.61H x 21.75W x 3.68D (inches)
  • What's in it shop.aprilaire.com Maker's own page checked Oct 1, 2026
    MERV Rating: 11; Materials: Plastic, Synthetic Fiber
  • Packs shop.aprilaire.com Maker's own page checked Oct 1, 2026
    Package sizes: 1-pack UK311; 2-pack UK311 02
Show all 16 sources

Which filter fits

  1. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    Compatible Models: 1310, 2310, 3310, 4300, U131, U233
  2. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    Compatible Models: 1310, 2310, 3310, 4300, U131, U233
  3. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    Page for the U131 (per its URL): Replaces AprilAire 1310 Whole-House Air Purifier
  4. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    Product 'AprilAire UK311 (Replaces 310) MERV 11 TriPure Filter + Upgrade Rails', SKUs UK311, UK311 02
  5. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    The AprilAire UK311 replaces the sunsetting AprilAire 310 Filter; 'Your next subscription will be the 3F311 - filter only'
  6. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    Product 'AprilAire UK313 (Replaces 313) MERV 13 TriPure Filter + Upgrade Rails', SKUs UK313, UK313 02
  7. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    The AprilAire UK313 replaces the sunsetting AprilAire 313 Filter; 'Your next subscription will be the 3F313 - filter only'

How many

  1. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    INCLUDED IN THE BOX: (1) U131 Air Purifier (1) 3F311 Air Filter; Filter Nominal Dimensions (H x W): 20 x 20 (inches)

How often

  1. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    LONG FILTER LIFE – One filter lasts up to 12 months
  2. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    LONG FILTER LIFE – One filter lasts up to 12 months

Size

  1. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    Nominal Measurements: 20H x 20W x 4D (inches) Actual Measurements: 20.61H x 21.75W x 3.68D (inches)
  2. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    Nominal Measurements: 20H x 20W x 4D (inches) Actual Measurements: 20.61H x 21.75W x 3.68D (inches)

What's in it

  1. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    MERV Rating: 11; Materials: Plastic, Synthetic Fiber
  2. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    MERV Rating: 13; Materials: Plastic, Synthetic Fiber

Packs

  1. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    Package sizes: 1-pack UK311; 2-pack UK311 02
  2. shop.aprilaire.com Maker's own page checked Oct 1, 2026
    Package sizes: 1-pack UK313; 2-pack UK313 02