Custom Air Filters — Any Size, All Materials, Same-Day Quote

Shop Custom Filters — All Types and Materials

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Why Custom-Size Filters?

Most commercial and industrial HVAC equipment is not designed around standard 16×20 or 20×25 nominal filter dimensions. Economizers, packaged rooftop units (RTUs), air handling units (AHUs), custom-built plenums, and industrial process ventilation systems all use filter openings sized to the specific unit geometry — and those dimensions rarely hit a standard nominal size. The result is that the correct filter for a given piece of equipment is, by definition, a non-standard size that must be fabricated to fit.

Even in residential applications, custom filters arise in older homes where return air openings were cut to odd dimensions before standard filter sizing was common, or in new construction where an architect specified a custom return grille dimension for aesthetic reasons. The common thread: a filter that doesn’t fit its slot properly does not filter. A filter that is 1/4” too small on either dimension leaves a gap that bypasses the media entirely, routing unfiltered air straight to the equipment it is supposed to protect.

Metal Air Filters’ custom fabrication capability eliminates the gap problem. We cut to your exact face dimensions, build to your specified depth, and ship a filter that fits the slot it was built for. Because our filters are washable and reusable, the one-time cost of a custom-fabricated metal mesh filter — slightly higher than a stock filter due to setup — is recovered quickly against the ongoing cost of custom-size disposables, which must be special-ordered and stockpiled at a premium.

Custom Filter Types Available

We fabricate custom filters in every type and material in our standard product line. Select the type that matches your application requirements.

Custom Aluminum Mesh Filters

Multi-ply corrugated aluminum mesh in an aluminum frame. Available in 1/2”, 1”, 2”, and 4” depths. The most common custom filter type — used in commercial HVAC economizers, packaged rooftop units, custom air handling units, and residential applications with non-standard slot dimensions. Lightweight, corrosion-resistant, UL 900 Class 1 rated, continuous service to 275°F. Products: 1/2” custom aluminum, 1” custom aluminum, 2” custom aluminum, 4” custom aluminum.

Custom Galvanized Steel Mesh Filters

Multi-ply corrugated galvanized steel mesh in a galvanized frame. Available in 1”, 2”, and 4” depths. Heavier than aluminum with higher structural stiffness; used in industrial applications, make-up air units, and commercial systems where sturdier construction is required or where the equipment spec calls for steel. Same media specification as aluminum mesh — equivalent dust arrestance and pressure drop performance. Products: 1” custom galvanized, 2” custom galvanized, 4” custom galvanized.

Custom Stainless Steel Mesh Filters

Multi-ply corrugated Type 304 stainless steel mesh in a stainless frame. Available in 1”, 2”, and 4” depths. Specified for high-temperature applications (rated to 1,000°F), coastal or corrosive environments where aluminum or galvanized alloys are inadequate, food and pharmaceutical process air systems requiring NSF-compatible materials, and industrial filtration applications involving oils, coolants, or chemical mists. Products: 1” custom stainless, 2” custom stainless, 4” custom stainless.

Custom Mist Eliminator Filters

Chevron-corrugated mesh media specifically designed to capture and drain entrained liquid droplets (water, oil mist, coolant mist) from an air stream. Available in aluminum, galvanized steel, and stainless steel; in 1”, 2”, and 4” depths. Used in cooling tower intakes, evaporative coolers, spray booths, wash stations, compressed air systems, and any application where liquid carryover is present in the air stream. Custom-fabricated to your exact face dimensions and housing geometry. Products: 1” aluminum mist eliminator, 2” aluminum mist eliminator, stainless mist eliminator.

Custom Electrostatic Filters

Self-charging electrostatic media in an aluminum frame. Available in 1/2”, 1”, and 2” depths. Electrostatic filters use the triboelectric effect — airflow charging the media electrostatically — to attract and capture fine particles that would pass through a standard mesh filter, achieving MERV 8 equivalent performance without a power supply. Custom-cut to any face dimension; used in residential HVAC with non-standard filter slots where higher filtration efficiency is required. Products: 1/2” custom electrostatic, 1” custom electrostatic, 2” custom electrostatic.

Custom Media Pad Holding Frames

Rigid aluminum retainer frames designed to hold a replaceable media pad (fiberglass, polyester, or specialty media) in a filter slot or duct opening. Available in 1” and 2” depths. Custom-fabricated to your exact frame opening dimensions. Used in commercial and industrial systems where the equipment uses a pad-and-frame filter assembly rather than a cartridge-type filter, and where the existing frame has been damaged or where a new frame is needed for a custom duct section. Products: 1” custom pad frame, 2” custom pad frame.

Custom Foam Filters

Open-cell polyurethane foam filter media in a custom-cut frame. Available in 1/2”, 1”, and 2” depths. Foam filters provide MERV 4 equivalent filtration with extremely low pressure drop — used in range hoods, exhaust vents, equipment cooling openings, low-velocity applications, and anywhere a very soft, compliant filter is required to fill an irregular opening. Washable and reusable. Products: 1/2” custom foam, 1” custom foam, 2” custom foam.

How to Measure for a Custom Filter

Accurate measurement is the most important step in ordering a custom filter. A filter built to wrong dimensions will either not fit the slot or leave a bypass gap — and because each custom filter is built to your spec, it cannot be returned and exchanged for a different size. Take the time to measure correctly before ordering.

What to Measure

• Width and Height (face dimensions): Measure the filter slot opening — not the equipment frame, not the duct, but the actual opening that the filter will sit in — to the nearest 1/16”. Measure both dimensions twice (at opposite ends of each axis) to confirm the slot is square. If the measurements differ, use the smaller value to ensure the filter will clear the slot on both sides.
• Depth (thickness): Measure the depth of the filter slot or housing from the retaining face to the back stop. This is the maximum depth a filter can be without hitting the back of the housing. Standard depths are 1/2”, 1”, 2”, and 4”. If your slot depth falls between two standard depths, use the smaller depth to ensure clearance.
• Existing filter dimensions (if available): If you have an existing filter to replace, measure its actual physical dimensions — not the nominal size printed on the frame, which may differ from the true face size by up to 1/2”. We will match the actual dimensions exactly.

Dimensions Format for Ordering

Provide dimensions in the format Width × Height × Depth, with fractional inches in standard fractions (1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8). Example: 17-3/4 × 22-1/2 × 1. If you have a dimension that falls on an odd fraction (11/16, 13/16), round to the nearest 1/8” for ordering. Our standard fabrication tolerance is ±1/16”, which covers any variation within the nearest 1/8” rounding.

OEM Part Numbers

If you have an OEM part number from a Carrier, Trane, York, Lennox, or other manufacturer’s filter, contact us with the part number and we can identify the exact replacement dimensions from our cross-reference database. Many commercial rooftop unit filter part numbers correspond to specific exact dimensions we already have on file. We will quote same business day on any part number cross-reference request.

Custom Filter Specifications

Common Applications Requiring Custom Filters

How to Order a Custom Filter

Option 1 — Order Directly Online

Select the product type and depth from the filter grid above. On the product page, enter your exact width, height, and depth dimensions in the order form fields, add to cart, and check out. We receive your order with your dimensions, fabricate to spec, and ship. This is the fastest path for standard filter types where you are confident in your measurements.

Option 2 — Request a Quote

Contact us with your dimensions, filter type, depth, quantity, and any relevant application details (temperature, chemical exposure, OEM part number, equipment model). We respond same business day with a firm price. Quoting is recommended when: you need multiple filter types in one order, you have an OEM part number to cross-reference, you have unusual dimensions or tight tolerances, you need a large quantity, or you have questions about which filter type is correct for your application.

Option 3 — Send a Sample

If you have a worn or damaged filter you want to replace but cannot measure the slot directly, mail us the existing filter. We will measure it accurately, confirm the dimensions with you, and fabricate the replacement. Contact us first to arrange sample submission — provide your return shipping address and we will include the original sample with your order shipment.

Frequently Asked Questions

What is the minimum order quantity for a custom filter?

One piece. We do not have a minimum quantity requirement for custom filters. Whether you need a single replacement filter for an older piece of equipment or a large quantity for a fleet of commercial units, we fabricate to order at any quantity. Unit pricing does improve on larger quantities — contact us for a volume quote if you need more than 10 pieces.

How long does it take to receive a custom filter?

Custom filters are fabricated and shipped within 1–2 business days of order for standard configurations. Once shipped, delivery time depends on your location and selected shipping method. If you have an urgent timeline or a rapid equipment startup requirement, contact us and we will confirm the fastest available ship date.

Can you match an OEM filter exactly?

Yes. We cross-reference OEM filter part numbers from Carrier, Trane, York, Lennox, and other major manufacturers to exact physical dimensions and media specifications. We have an extensive internal part number database built from years of quoting commercial HVAC filter replacements. Provide the OEM part number (with manufacturer name) and we will confirm the exact dimensions and match the media depth and alloy specification. Many OEM exact-size replacements are also listed as stocked items in our catalog — contact us with your part number and we will check stock first before quoting fabrication.

What is the fabrication tolerance on custom filters?

Standard tolerance is ±1/16” on all face dimensions. This means a filter ordered as 17-3/4”×22-1/2” will be delivered between 17-11/16” and 17-13/16” wide and between 22-7/16” and 22-9/16” high. This tolerance is appropriate for the vast majority of filter slot fits. Tighter tolerances (±1/32” or closer) are available for precision applications — contact us to discuss if your slot requires a tighter fit.

I need a filter for a Carrier / Trane / York rooftop unit. Do you have it?

Probably, yes. We carry a large catalog of exact-size replacements for commercial RTU filters, including many Carrier, Trane, York, and Lennox part numbers. Check the custom-size filter catalog first — if your dimension and part number is listed, add to cart directly. If it is not listed, send us the part number and we will fabricate to spec same business day.

Which filter type should I choose — aluminum, galvanized steel, or stainless?

For standard residential and commercial HVAC: aluminum is the correct choice. It is lightweight, corrosion-resistant without a coating, and the standard product in our catalog. For heavy industrial or high-strength applications where structural rigidity matters: galvanized steel. For high-temperature applications above 275°F, corrosive environments (coastal salt air, chemical exposure), or food/pharmaceutical process air: stainless steel. If you are unsure, aluminum handles the majority of applications correctly.

Can I order a custom filter in a depth not listed (e.g., 3 inches or 1.5 inches)?

Our standard production depths are 1/2”, 1”, 2”, and 4”. Non-standard depths (1.5”, 3”, etc.) can be produced on request — contact us with your requirements and we will confirm feasibility and pricing. In most cases, a 2” filter is the correct specification for slots between 1.5” and 2.5” in depth, because filter housings in that range are typically designed to accept a 2” filter with some clearance tolerance.

Do custom filters qualify for free shipping?

Yes. Custom filters ship free on orders of $99 or more, the same as all Metal Air Filters products. Most single-piece custom filters for commercial applications meet the $99 threshold. If your order is below the threshold, standard shipping rates apply at checkout.

Are custom filters returnable?

Custom filters are fabricated to your specified dimensions and cannot be restocked for resale to another customer. For that reason, we do not accept returns on custom filters due to incorrect dimensions provided by the customer. We strongly recommend double-checking your measurements before ordering. If you are uncertain about your dimensions, request a quote and confirm with us before completing your order — we are happy to talk through your measurement process and confirm the correct specification with you. If there is a fabrication error on our end — we built to different dimensions than specified — we replace the filter at no charge.