Whole-Home Media● In stock
18×24×4Air Filter
Actual size: 17.5″ × 23.5″ × 3.63″
Fits any 18x24x4 slot or return grille. Order by the size printed on your old filter.Also sold as 24x18x4.
Fits any 18x24x4 slot or return grille. Order by the size printed on your old filter.Also sold as 24x18x4.
- Free shipping $100+
- Fit guarantee
- Picked by HVAC techs
Choose your protection level
Pack size (bigger packs save more)
18x24x4 · MERV 11 · 2-Pack$75.98$69.99
Or subscribe: $25.99/filter delivered, never think about it againMERV 11 · 2-Pack
$69.99
Common questions about 18x24x4
What is the actual size of a 18x24x4 filter?+
The nominal size printed on the frame is 18x24x4, but the filter actually measures 17.5" × 23.5" × 3.63". 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 18x24x4?+
MERV 8 handles everyday dust. MERV 11 is our most popular, it captures pet dander and pollen. MERV 13 adds smoke, bacteria, and virus-carrier capture. When in doubt, call us, a real HVAC tech answers.
How often should I change a 18x24x4 filter?+
Deep-pleat media filters like this 4-inch typically last 6-12 months. Check it at each season change.
Is a 24x18x4 the same as a 18x24x4?+
Yes, 18x24x4 and 24x18x4 are the same filter; the dimensions are just written in a different order. This filter fits both.
Nearby sizes
1″ pleated
18×24×1
Air Filter
MERV 8 · 11 · 13
$12.99single
$6.50/filter in 12-packs
2″ pleated
18×24×2
Air Filter
MERV 8 · 11 · 13
$16.99single
$8.46/filter in 12-packs
4″ media
18×25×4
Air Filter
MERV 8 · 11 · 13 · 16
$32.99single
$28.00/filter in 4-packs
Top Seller4″ media
16×25×4
Air Filter
MERV 8 · 11 · 13 · 16
$32.99single
$28.00/filter in 4-packs