Actual Size: 11.5x11.5x3.63
Free Delivery 
Factory-Direct Low Prices, Made in the USA
Hassle-Free Returns & Free Exchanges
RESIDENTIAL AND/OR COMMERCIAL USE
Change Every 3 Months
Actual Size: 11.5x11.5x3.63
Free Delivery Factory-Direct Low Prices, Made in the USAHassle-Free Returns & Free ExchangesRESIDENTIAL AND/OR COMMERCIAL USE
Change Every 3 Months
Actual Size: 11.5x11.5x3.63
Free Delivery Factory-Direct Low Prices, Made in the USAHassle-Free Returns & Free ExchangesRESIDENTIAL AND/OR COMMERCIAL USE
Change Every 3 Months
At Filterbuy, we don't cut corners—we craft high-quality air filters right here in the USA and ship them to your doorstep for free. No delays, no gimmicks—just clean air, made easy. With thousands of five-star reviews and filters built for real life & every HVAC system, it's no wonder why over 4 million families trust Filterbuy.
Proudly Made In The USA
Fast, Free Shipping on Every Order
Premium Materials That Go The Distance
85,000+ 5-Star Reviews From Happy Customers
Save Up to 70% Per Filter with Packs
Measure length × width × depth with a tape measure to find the actual size.
Round up each dimension to the nearest whole number to get the nominal size. Example: 11.5x11.5x3.63 in → 12x12x4 nominal.
Search by nominal size on our site for the best fit.
4″ filters offer better airflow and a longer life (6–9 months) than standard 1″ or 2″ filters — ideal for homes with pets or allergy concerns.
Sizing note:
If the filter you buy doesn't fit, we'll send you a better size.
MERV stands for Minimum Efficiency Reporting Value—but don't let the technical name fool you. It's just a way to rate how well an air filter traps stuff like dust, pollen, pet dander, and smoke. The higher the MERV number, the more particles it catches—and the cleaner your air will be.
Comparable to:FPR: 4-7
MPR: 600-1000
Dust & Debris
Dust Mites & Particles
Pollen
Mold
Lint
Dander
Comparable to:FPR: 6-9
MPR: 1200-1550
Dust & DebrisDust Mites & ParticlesPollenMoldLintDander
Smoke & Smog
Comparable to:FPR: 10
MPR: 1900-2800
Dust & DebrisDust Mites & ParticlesPollenMoldLintDanderSmoke & Smog
Bacteria
We build every Filterbuy filter to deliver reliable 90-day performance—thanks to smart design and premium materials that do the heavy lifting. Here's what makes the difference:
More pleats = more surface area to capture dust and debris, keeping your air cleaner longer.
Pleats are magnetized to attract and trap microscopic particles—like pet dander, pollen, and smoke.
Engineered to resist warping in extreme temperatures and high humidity.
A layer of metal reinforcement keeps pleats evenly spaced and structurally sound—no sagging, even at high airflow.
Assembled with care. Built to perform. Ships fast, free, and reliably from our U.S. facilities.
Turn Off Your HVAC SystemSafety first.
Remove The Old FilterLook for the airflow arrow and make note of the direction.
Slide In Your New FilterArrow should point toward the system (same direction as before).
Turn Your System Back OnAnd enjoy the fresh, clean air.
Not all air filters are created equal. Pleated filters don't just last longer—they actually clean your air better. Here's how they stack up:
Efficiency:
High (MERV 8–13) – Traps more particles
Lifespan:
90 days – Long-lasting performance
Air Quality:
Excellent – Cleaner, healthier air
Materials:
Recyclable and durable
Efficiency:
Low (MERV 4 or less) – Misses small stuff
Lifespan:
30 days or less – Replace often
Air Quality:
Minimal – Basic protection only
Materials:
Thin, flimsy, and not recyclable
Pleated filters are a no-brainer—more protection, less hassle, and better air for your home.
Changing your filter on time keeps your HVAC system running efficiently—and helps protect your lungs from dust, allergens, and airborne irritants. Here's how often to swap it out based on your needs:
For most homes without pets or special air quality concerns. Great for general upkeep and energy efficiency.
Shedding fur, dander, and allergy triggers can build up fast. Changing your filter every two months helps keep the air fresher and symptoms at bay.
For households affected by smoke, pollution, or respiratory conditions, monthly changes ensure maximum protection.
| Nominal Size | 12 x 12 x 4 inches |
| Actual Size | 11.5 x 11.5 x 3.63 inches |
| Filter Type | Pleated |
| Media | Electrostatically Charged |
| Frame | Beverage Board |
| MERV Ratings Available | 8, 11, 13 |
| Lifespan | Up to 12 Months |
| Origin | Made in USA |
By Michelle Wan | Reviewed by David Clark, Licensed HVAC Technician | Published September 2, 2026 | Updated September 2, 2026
A 12x12x4 MERV 11 air filter is a four-inch pleated filter that captures 95% of airborne particles. The nominal size 12x12x4 is the ordering name, and the actual cut is 11.50 by 11.50 by 3.63 inches, a little smaller by design so it slides into the slot. MERV 11 is Filterbuy’s Superior tier, built for allergy sufferers and for homes with pets or pollen. Check your HVAC manual to confirm which MERV tier your system takes, the same way you’d confirm a size.
The actual cut of a Filterbuy 12x12x4 is 11.50 by 11.50 by 3.63 inches. Nominal 12x12x4 is the ordering name, and the cut runs smaller by design so the filter slides in.
MERV 11 is Filterbuy’s Superior tier and captures 95% of airborne particles. It’s comparable to MPR 1000–1200 and FPR 7.
MERV 11 is the tier for allergy sufferers, and for households with pets or pollen.
A four-inch filter holds more dust than a one-inch of the same size, so you won’t change it as often.
Check your HVAC manual to confirm which MERV tier your system takes, the same way you’d confirm a size.
A 12x12x4 MERV 11 air filter is a four-inch pleated filter for a furnace, air conditioner, heat pump, or air handler. MERV stands for Minimum Efficiency Reporting Value, the industry scale that rates how much a filter captures. MERV 11 is Filterbuy’s Superior tier, and it captures 95% of airborne particles.
Depth is what separates this filter from a one-inch panel. Deeper pleats pack more media into the same opening, so the filter holds more dust and you won’t swap it as often. Filterbuy cuts, pleats, and frames every 12x12x4 to order in our own US plants.
MERV 11 compares to MPR 1000–1200 and FPR 7. MPR is 3M’s rating system and FPR is Home Depot’s. Neither belongs to Filterbuy, and neither is an industry standard the way MERV is. Check your HVAC manual to confirm which MERV tier your system takes, the same way you’d confirm a size.
Finding your size takes about ten seconds. Pull the old filter and read the numbers printed along the frame edge. That’s your size, and 12x12x4 is what you order.
If there’s no old filter, measure the slot instead and round up to the nearest inch. Nominal size is the ordering name. The actual cut of a 12x12x4 is 11.50 by 11.50 by 3.63 inches, and that bit of clearance is what lets the frame seat without binding. Every pleated filter carries both numbers.
If your size isn’t listed, Filterbuy cuts custom sizes to the eighth of an inch. Browse 12x12x4 MERV 11 air filters to check stock and pack sizes.
Each tier does a different job. MERV 8 is the standard choice for most homes. MERV 11 is built for allergy sufferers and for households with pets or pollen. MERV 13 is the tier for smoke.
Check your HVAC manual to confirm which MERV tier your system takes, the same way you’d confirm a size.
Compare the full 12x12x4 MERV 8 air filters and 12x12x4 MERV 13 air filters ranges side by side.
A 12x12x4 usually sits in a ceiling or high-wall return grille rather than down at the air handler. If you found one, the house probably has more, so check the other hallways and ceilings before you order.
That’s also why four-inch media earns its place in this size. These grilles sit overhead, and fewer changes a year means fewer trips up the ladder.
MERV 11 is Filterbuy’s tier for allergy sufferers. It captures 95% of airborne particles. The pleated media traps pollen, pet dander, mold spores, and dust mite debris.
The American College of Allergy, Asthma & Immunology recommends a disposable filter rated MERV 11 to 13 for allergy households, and the American Lung Association publishes similar guidance on home air cleaning.
A filter is one part of the picture. Central filtration only works while the blower runs, which is why plenty of households set the fan to circulate instead of auto. If someone at home has questions about allergies or asthma, talk to a doctor. Check your HVAC manual to confirm which MERV tier your system takes, the same way you’d confirm a size.
Check it monthly and replace it when the pleats look loaded. Here’s the quickest test: hold the filter up to a light, and if light doesn’t pass through the pleats, put a fresh one in.
Four-inch filters run longer than one-inch because the deeper pleat pack holds more dust. Pets, indoor smoking, construction nearby, and wildfire smoke all load a filter faster, so a house with two dogs won’t run the same schedule as a house without.
ENERGY STAR advises checking monthly during heavy heating and cooling months and changing at least quarterly.
Filterbuy sells this size as single units and in 2, 4, 6, and 12 count multi-packs. A 4 pack covers a multi-return home for one change cycle, and a 12 pack is about a year of stock.
Per-filter cost drops as pack size rises, and shipping is fast and free 2-day delivery to most US states. You can also read how MERV 11 air filters perform across other sizes.
EIA surveyed 123.5 million U.S. homes.
88 percent use air conditioning, per EIA’s 2020 Residential Energy Consumption Survey.
Two-thirds run central AC or a central heat pump as their main equipment.
Source: U.S. Energy Information Administration, 2020 Residential Energy Consumption Survey
Filter manufacturers typically recommend replacement every 60 to 90 days, per EPA.
EPA advises changing more often when a filter looks heavily soiled at replacement.
Source: U.S. Environmental Protection Agency, Guide to Air Cleaners in the Home
6.5 percent of U.S. children under age 18 currently have asthma, per CDC.
Figure drawn from the 2024 National Health Interview Survey.
Source: CDC National Center for Health Statistics, FastStats Asthma
A Filterbuy 12x12x4 measures 11.50 by 11.50 by 3.63 inches. The 12x12x4 on the box is the nominal size, which is just the ordering name.
Filterbuy cuts custom sizes to the eighth of an inch, so you can order the exact dimensions your slot needs. Measure the opening, round to the nearest eighth, and order that.
No. A four-inch filter needs a housing built for it. Force one into a one-inch track and the frame bends and air slips past the media instead of going through it.
The arrow follows the air, so it points toward the blower and away from the room. In a ceiling return that means the arrow points up into the duct.
MERV 8 is the standard choice for most homes, MERV 11 is built for allergy sufferers and homes with pets or pollen, and MERV 13 is the tier for smoke. Check your HVAC manual to confirm which MERV tier your system takes, the same way you’d confirm a size.
MERV 13 is the tier for smoke. If smoke is what you’re dealing with, that’s the one to order in this size.
Actual size: The true measured cut of a filter, printed in smaller type on the frame. For a 12x12x4, that is 11.50 by 11.50 by 3.63 inches.
FPR: Filter Performance Rating, a 1 to 10 scale used to rate air filter performance.
MERV: Minimum Efficiency Reporting Value, the industry scale from 1 to 20 that rates how much a filter captures.
MPR: Microparticle Performance Rating, a scale used to rate how effectively an air filter captures small airborne particles.
Nominal size: The rounded name used to order a filter, such as 12x12x4. It always runs a little larger than the actual cut.
