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Advanced Thermal Concepts LLC
All filters/Sizes/1-inch/19x21x1
1-Inch Pleated

19×21×1Air Filter

Actual size: 18.5″ × 20.5″ × 0.75″
Fits any 19x21x1 slot or return grille. Order by the size printed on your old filter.Also sold as 21x19x1.
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  • Picked by HVAC techs
19x21x1 · MERV 8 · 11 · 13

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Common questions about 19x21x1

What is the actual size of a 19x21x1 filter?+

The nominal size printed on the frame is 19x21x1, but the filter actually measures 18.5" × 20.5" × 0.75". That undercut is intentional: it slides into your filter track without binding. Order by the nominal size printed on your old filter.

Which MERV rating should I pick for a 19x21x1?+

MERV 8 handles everyday dust. MERV 11 is our most popular. It captures pet dander and pollen. MERV 13 adds smoke and the finest everyday particles, and it's fine in modern systems (post-1995 blowers). When in doubt, call us. A real HVAC tech answers. Compare MERV 8, 11 and 13.

How often should I change a 19x21x1 filter?+

Every 30 to 90 days: monthly with multiple pets or allergies, every 60 days with one pet, every 90 days otherwise. See the schedule by household type.

Is a 21x19x1 the same as a 19x21x1?+

Yes, 19x21x1 and 21x19x1 are the same filter; the dimensions are just written in a different order. This filter fits both.

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