Representative image — you’ll receive the exact size you select. Actual dimensions are in the specs.
Exact Filters
30-1/4x18-1/8x1 Exact Filters Pleated MERV 13 (12 pack)
- MERV 13
- Pack 12 Filters
- Free shipping over $50
- 30-day returns
- Secure checkout
- US-based expert support
Couldn't load pickup availability
Need a 2″ or 4″ version of 30-1/4x18-1/8x1?
Need this in 2″ or 4″ depth? Both are available, made to specification. 2″ ships as a case of 12; 4″ ships as a case of 6 due to volume. Request a quote and we’ll come back with pricing and lead time.
Product details
This 30-1/4 x 18-1/8 x 1″ Exact Filters® air filter is manufactured to your exact dimensions, eliminating the guesswork of matching an off-the-shelf filter to a non-standard 30-1/4 x 18-1/8 x 1″ opening.
Even a quarter-inch of gap around a filter can allow a significant percentage of return air to bypass the media entirely, which is why the exact fit matters as much as the filter's efficiency rating.
At MERV 13, this filter removes a significantly larger share of fine particulate from your return air than standard mid-efficiency ratings — including smoke, bacteria-sized particles, and the fine dust that tends to resettle faster after cleaning. Because the media is denser, a properly sized HVAC system matters: check your blower's static-pressure headroom before upgrading.
Specifications
- Nominal size: 30-1/4 x 18-1/8 x 1″
- Actual dimensions: 30-1/4 x 18-1/8 x 3/4″
- Efficiency rating: MERV 13
- Quantity: 12 filters per carton
The 30-1/4 x 18-1/8 x 1″ dimension is one of the many non-standard sizes we make on demand, serving both retrofit installations in older homes and light-commercial properties where the return housing dates to an older era of HVAC construction.
Features
- Orientation arrow printed on the frame to ensure correct airflow direction at install
- Suitable for forced-air furnaces, central AC, heat pumps, and packaged HVAC systems
- Made to your exact 30-1/4 x 18-1/8 x 1″ specification — no trimming or taping required at installation
- Sold as a 12-pack so you have a full year of replacements on hand
Same 30-1/4 x 18-1/8 x 1″ size, different efficiency rating
| MERV 1-4Basic dust-stop | MERV 8Standard efficiency | MERV 11Enhanced efficiency |
|
Need 30-1/4 x 18-1/8 x 2″ or another depth? This size is available in other depths we don't stock online — reach out and our team will quote it for you, typically same business day.
|
Made for your slot — not forced to fit it
Exact Filters® are manufactured to your measurements. No trimming, no weatherstripping, no “close enough.” Built on the back of 50 years of HVAC filtration experience.
Built to your exact dimensions
Measured in 1/8″ increments. The frame matches your slot opening so the media fits where it's supposed to — no shimming, no weatherstripping.
Eliminates filter bypass
When a loose filter lets air slip around the frame instead of through the media, your filter underperforms its MERV rating — sometimes by 20-40%. A precise fit closes that gap so your filter does the job you paid it to do.
More detail on filter bypass further down this page.
If your filter slot doesn't match a standard size, you're exactly who these are for
Non-standard slots are more common than the big-box filter world wants to admit. Here's who typically lands on these pages.
Homes built before filter sizes standardized (roughly pre-1990) often have slot dimensions like 30 1/4 x 18 1/8 x 1 inches that don't match anything in a retailer's catalog. Regional manufacturers didn't converge on today's standard dimensions until the industry consolidated in the 1990s.
Broan, Nutone, obsolete units, and discontinued models often used proprietary slot dimensions that never made it into the standard-size catalog. If you can't find your filter anywhere, it's probably one of these.
When an HVAC installer frames a filter slot in the field — especially during a retrofit — they cut to fit the space, not to match a standard filter. The result: a slot that works perfectly for the system but nothing off the shelf fits.
Adding HVAC to a space that wasn't built for it — finished basements, converted attics, additions — almost always produces non-standard slot dimensions. The new system respects the existing envelope, so the filter has to respect the slot.
Mid-century commercial buildings, converted spaces, schools, clinics, and multifamily properties with older AHUs routinely have slot dimensions outside the standard catalog. Volume orders for these properties are a significant share of our Exact Filter business.
Clinical spaces, labs, server rooms, and any environment where air bypass around the filter is a compliance or performance issue — not just a nuisance. If MERV rating matters for your space, slot fit matters too.
Filter bypass — why a loose filter wastes your MERV rating
Filter bypass is what happens when air flows around your filter instead of through it. If there's a gap between the filter frame and the slot — even a small one — air takes the path of least resistance, which is the gap. That air never gets filtered.
The math is punishing. A filter rated MERV 11 that's bypassed by 15% of the airflow effectively performs closer to MERV 8. A MERV 13 with 20% bypass performs closer to MERV 10. This is documented in ASHRAE literature and is a standard problem in field filter performance.
The usual workarounds don't actually work well. Foam weatherstripping around the filter edge compresses unevenly and shifts during operation. Undersized filters with gap-filler material block part of the face area, reducing effective filtration surface. Oversized filters that get forced into the slot warp, reducing media effectiveness and creating turbulence.
Bypass doesn't just waste your MERV rating — it eats your equipment. Unfiltered air carries dust, pet dander, and construction debris straight into the parts of your system that aren't supposed to see any of it. Evaporator coils cake with buildup that reduces heat transfer, meaning the compressor works harder and runs longer. Blower wheels get coated and throw off balance, accelerating bearing wear. A season of 15–20% bypass can add up to a coil cleaning service call that runs several hundred dollars; a few years of it can shorten compressor life or require coil replacement that runs into the thousands. If your filter standard isn't perfect, it's not just air quality you're sacrificing — it's the equipment behind the filter slot.
The fix is a filter built to your slot. That's what Exact Filters are. The frame meets the slot edges with the right tolerance — no crushing, no gap. The filter captures the air it's supposed to capture, at the MERV rating you paid for.
Cases of 12. Pallets for portfolios. Standing orders for the properties that need them.
Exact Filters ship as cases of 12 — the quantity commercial buyers, facility managers, and serious maintenance operations order by default. Older schools and clinics run through them at the ASHRAE-recommended 90-day cadence. Multifamily properties stock them in the maintenance room. Property management companies consolidate the spec across their entire portfolio.
We'll quote volume pricing, set up net-terms or tax-exempt accounts, consolidate mixed sizes under one PO, and schedule standing delivery matched to your change-out cycle.
Homeowners stocking a multi-year supply get the same case pricing — no minimum negotiation required.
What customers say about 30-1/4x18-1/8x1 Exact Filters Pleated MERV 13 (12 pack)
Questions specific to Exact Filters
Ordering a custom-made filter is different from grabbing a stocked size. Here's what customers ask before they order.
Not sure if 30-1/4x18-1/8x1 Exact Filters Pleated MERV 13 (12 pack) matches your slot?
Send us your measurements or the HVAC unit model. Our team has two decades of sizing Exact Filters for homes and facilities — we'll tell you if the size you're ordering is right, or flag if something looks off.