How to Choose a Custom Air Filter Supplier: A Facilities Manager’s Guide
How to compare custom air filter manufacturers and suppliers based on fit, manufacturing capability, lead times, inventory, filtration performance,
delivery, and total cost.
Managing HVAC filtration across a commercial facility is rarely as simple as ordering a few common filter sizes.
Older equipment, renovations, different air-handler manufacturers, multiple buildings, and changing filtration requirements can leave facilities teams managing dozens—or even hundreds—of filter sizes and configurations.
Some are standard. Some are fractional. Some are exact sizes. Some may have been installed decades ago and no longer match anything sitting on a distributor’s shelf.
That is where choosing the right custom size air filter supplier becomes important.
A good supplier should do more than make an unusual filter. The right partner can help facilities teams maintain proper filter fit, shorten lead times, simplify purchasing, organize complex filter schedules, reduce unnecessary inventory, and reliably get the right filters to the right facility.
This guide explains what facilities managers and procurement teams should look for when comparing custom size filters, custom air filter manufacturers, and commercial filter suppliers.
Need Custom Size Air Filters?
Manufactured in New Hampshire. Custom sizes. Extensive inventory. Reliable delivery throughout New England.
If you already have a filter list, spreadsheet, previous order, or equipment schedule, send it to Airex.
You don't need to reorganize everything first.
Our team can review your current sizes, quantities, MERV ratings, filter types, and delivery requirements and provide a competitive quote for both standard and custom filtration.
What Are Custom Size Air Filters?
Custom size air filters are HVAC filters manufactured to dimensions outside commonly stocked nominal sizes.
Standard commercial filters are often ordered in familiar dimensions such as 16x20x2, 16x25x2, 20x20x2, 20x25x2, or 24x24x2.
But commercial and industrial HVAC systems don't always cooperate with standard sizing.
A facility might require filters such as:
15½ x 19½ x 2
17 x 23 x 1
19¾ x 23¾ x 2
21 x 26 x 2
Fractional dimensions
Unusual filter depths
Exact-size filters made for an existing rack
Custom filters are particularly common in older buildings, renovated facilities, specialized equipment, and portfolios containing HVAC systems installed across different generations.
Rather than forcing a close standard size into the equipment, a custom filter can be manufactured to properly fit the existing filter rack.
Why Proper Air Filter Fit Matters
Filter dimensions aren't just a purchasing detail.
If a filter doesn't properly fit the rack, air can potentially travel around the filter rather than through the filtration media.
That bypass can undermine the purpose of installing a higher-performing filter in the first place.
Poor filter fit can contribute to:
Air bypass
Dirt accumulation on coils
Increased system contamination
Additional HVAC maintenance
Reduced filtration effectiveness
Premature equipment fouling
Poor system performance
For facilities managers, the goal shouldn't simply be to find a filter that is "close enough."
The goal is to have the correct filter for the equipment.
This becomes especially important in hospitals, laboratories, biotech facilities, universities, manufacturing plants, commercial properties, data centers, and other environments where HVAC reliability matters.
Nominal Size vs. Actual Filter Size
One of the most common sources of confusion when ordering commercial air filters is the difference between nominal size and actual size.
A filter labeled 20x20x2, for example, may physically measure slightly less than 20 inches by 20 inches by 2 inches.
That is intentional. Many standard HVAC filters are manufactured slightly undersized so they fit into equipment designed around nominal dimensions.
With custom filters, however, those differences become particularly important.
Nominal dimensions
The commonly referenced or labeled filter size.
Actual dimensions
The physical measurements of the filter itself.
Before ordering an unfamiliar custom size, confirm which dimensions you are working with.
If there is uncertainty, measure the existing filter carefully or talk with the supplier before placing a large order.
A small dimensional misunderstanding multiplied across 100 or 500 filters can become an expensive mistake.
7 Things to Look for in a Custom Air Filter Supplier
Not every filter supplier approaches custom filtration the same way.
Some companies primarily distribute standard products and outsource unusual sizes. Others have their own manufacturing capabilities.
Facilities and procurement teams should evaluate more than unit price.
1. Custom Manufacturing Capability
Start by asking a simple question:
Do you actually manufacture custom filters?
Direct manufacturing capability can provide greater control over dimensions, construction, production scheduling, special requirements, and turnaround time.
Ask prospective suppliers:
Which filter types can you manufacture in custom sizes?
What dimensions and depths are available?
Where are the filters manufactured?
Are custom sizes produced internally or outsourced?
Can you accommodate repeat custom requirements?
What happens if an unusual size is needed unexpectedly?
For facilities that regularly purchase non-standard filters, manufacturing capability can become a meaningful advantage.
2. Custom Filter Lead Times
Lead time matters.
A custom filter isn't particularly useful if it arrives after the planned filter change.
Facilities should understand a supplier's typical production timeline before an emergency occurs.
Ask:
What is your normal custom filter lead time?
Then go deeper.
Does lead time vary by product?
Can high-volume custom requirements be scheduled ahead?
Are rush orders possible when a facility discovers an unexpected requirement?
Can frequently purchased custom sizes be manufactured or stocked in advance?
The best supplier relationship allows the facility to plan routine purchases while still having someone to call when reality doesn't follow the plan.
3. Ability to Manage Large Filter Lists
Buying filters for one rooftop unit is a transaction.
Managing filtration across 10, 25, 50, or 100 buildings is a facilities-management problem.
Hospitals, universities, property portfolios, manufacturing campuses, school districts, and other large organizations may have hundreds of individual filtration requirements.
A supplier should be comfortable working with information organized by:
Facility → Building → Equipment → Filter Size → Filter Type → MERV Rating → Quantity
The goal is to make purchasing easier—not create another administrative burden for the facility team.
If you already maintain a large spreadsheet or filter schedule, ask whether the supplier can simply work from it.
4. Standard and Custom Filters From One Supplier
Custom filters are usually only one part of a facility's requirements.
A building may use common pleated filters in one air handler, odd sizes somewhere else, higher-efficiency final filters in another system, and specialty filtration elsewhere.
Depending on the facility, requirements may include:
Pleated air filters
Panel filters
MERV 10 filters
MERV 11 filters
MERV 13 filters
Higher-efficiency filters
HEPA filtration
Bag filters
Cartridge filters
Carbon filtration
Permanent filters
Specialty commercial or industrial filtration
Being able to consolidate more of those requirements with one supplier can reduce the number of purchase orders, shipments, vendors, invoices, and contacts a facility team needs to manage.
5. Inventory and Stocking Capabilities
Custom manufacturing solves one problem.
Inventory solves another.
Facilities managers should ask how the supplier handles products that are ordered repeatedly.
Some organizations prefer keeping substantial filter inventory onsite.
Others would rather have the supplier maintain product availability and replenish filters as needed.
For larger accounts, an effective inventory strategy can help reduce:
Emergency orders
Excess onsite inventory
Storage requirements
Duplicate purchasing
Missed filter changes
Long replenishment cycles
There is no single inventory program that works for every organization.
The important thing is having a supplier flexible enough to build a program around the facility rather than forcing every customer into the same purchasing model.
6. Delivery and Logistics
Making the filter is only part of the job.
Someone still has to get it to the building.
Facilities managers should understand how orders are delivered and what happens when multiple locations are involved.
Ask whether the supplier uses its own regional delivery operation, common carriers, parcel service, or outside freight companies.
For multi-site organizations, also ask:
Can individual orders be separated by facility or location?
Can filters be identified or labeled to simplify distribution?
Can multiple buildings receive scheduled deliveries?
Reliable logistics become increasingly important as a filtration program grows.
7. Filtration Performance
Custom dimensions should never mean compromising filtration performance.
The supplier still needs to provide the appropriate filter construction and efficiency for the application.
Important considerations can include:
MERV rating
Media
Filter depth
Initial resistance
Final resistance
Frame construction
Airflow conditions
Environmental conditions
Equipment requirements
Application requirements
The correct filtration solution depends on both the building environment and the HVAC system.
Facilities teams should evaluate fit, efficiency, pressure drop, construction, and application together rather than treating MERV rating as the only specification that matters.
Why Facilities Choose Airex for Custom Size Air Filters
Airex Filter Corporation has been serving the air filtration industry for more than 50 years.
From Hudson, New Hampshire, Airex combines custom filter manufacturing, standard filtration products, extensive inventory, and regional distribution under one roof.
That combination is important for facilities with complicated requirements.
Rather than purchasing standard filters from one company, odd sizes from another, and specialty filtration somewhere else, Airex can help facilities consolidate more of their filtration program with a single supplier.
Our team supports commercial and industrial customers with standard and custom filtration requirements including pleated filters, panel filters, higher-efficiency products, HEPA filtration, carbon filters, bag filters, cartridge filters, permanent filters, and other specialty filtration products.
For New England customers, Airex also combines local manufacturing with dependable regional delivery—including regular service into the Greater Boston market.
The objective isn't simply to sell another box of filters.
It's to make managing filtration easier.
Custom Filters Made for the Equipment You Actually Have
Not every air handler was installed last year.
Walk through a large hospital, university campus, manufacturing plant, or commercial portfolio and you may find HVAC equipment installed during multiple decades of expansions and renovations.
The resulting filter schedule can contain a mixture of:
Standard nominal sizes.
Exact sizes.
Fractional dimensions.
Unusual depths.
Older equipment requirements.
Different filtration efficiencies.
Different construction requirements.
That's the real world of commercial HVAC filtration.
Airex manufactures custom size filters for those real-world applications.
If you're unsure whether an existing filter is nominal or exact, our team can help review the requirement before you place the order.
One Facility Is Easy. A Portfolio Is Different.
The larger a facility portfolio becomes, the less filtration looks like buying a commodity and the more it resembles managing a supply chain.
That's especially true when each location has different equipment.
Airex works with organizations across industries such as:
Healthcare & Hospitals
Hospitals and healthcare facilities can contain numerous air handling systems, multiple filtration stages, different efficiencies, and large scheduled filter changes.
Biotech & Life Sciences
Research, laboratory, production, and controlled environments can require more specialized filtration and dependable supply.
Schools & Universities
Campuses frequently contain buildings constructed during different periods, resulting in a wide variety of HVAC systems and filter requirements.
Commercial Buildings
Office buildings and mixed-use properties need reliable filtration programs without creating unnecessary complexity for facilities teams.
Property Management
Multi-property operators benefit from centralized purchasing while still maintaining the unique requirements of individual buildings.
Manufacturing & Industrial
Industrial environments can introduce demanding airflow, contamination, process, and equipment requirements.
Data Centers
Filtration, airflow, equipment protection, and reliability are important considerations in mission-critical facilities.
HVAC Contractors
Contractors need access to standard products while also having a dependable source when an unusual custom size appears in the field.
Built in New Hampshire. Delivered Throughout New England.
Proximity can matter when you're managing HVAC filtration.
Airex manufactures and distributes air filtration products from Hudson, New Hampshire while serving facilities throughout New England and beyond.
For customers in Greater Boston, Airex operates regular delivery routes into the market.
That regional presence can become especially valuable when:
A scheduled shutdown changes.
A contractor discovers an unexpected size.
A mechanical room contains filters that aren't on the purchasing list.
A filter change needs to happen earlier than planned.
An order contains both standard and custom products.
Another building gets added to the requirement.
Those situations happen.
Your filter supplier should be prepared for them.
Questions to Ask Before Choosing a Custom Filter Supplier
When evaluating custom filter suppliers, facilities and procurement teams should ask:
Manufacturing
Do you manufacture custom filters directly?
Where are they manufactured?
What custom dimensions, depths, and filter types are available?
Lead Times
What is your normal production time?
Can recurring custom filters be planned ahead?
Can urgent requirements be accommodated?
Inventory
Do you maintain significant stock of standard products?
Can regularly purchased filters be stocked or scheduled?
Logistics
How are orders delivered?
Can you support multiple facilities?
Can shipments be separated by building or location?
Organization
Can you work from our existing filter spreadsheet?
Can products be organized by facility, building, unit, or other identifier?
Filtration
Which MERV ratings and product types are available?
Can you provide technical information when needed?
Pricing
Are quantity price breaks available?
Can pricing be established for recurring requirements?
Can you quote an entire filter schedule rather than individual products?
The answers to these questions often tell you more about a potential supplier than comparing one filter price.
Filter Price vs. Total Cost
Procurement teams should absolutely compare pricing.
But unit price is only one component of the actual cost of a filtration program.
Consider the cost of:
Incorrect filter sizes
Emergency purchases
Long lead times
Unexpected freight
Multiple suppliers
Excess inventory
Repeated purchase orders
Additional deliveries
Staff time spent managing problems
Filters that don't properly fit the equipment
A slightly lower unit price can quickly lose its advantage if the facility spends significantly more time managing the supplier.
For multi-location organizations in particular, reliability, organization, product availability, and logistics can be as important as the price printed on the quote.
Already Have a Filter Supplier? Benchmark Them.
You don't need to immediately change suppliers to determine whether there's a better option.
Let Airex benchmark what you're buying today.
Send us your current filter list, spreadsheet, recent purchase order, or purchasing schedule.
Our team can review your:
Sizes
Quantities
Filter types
MERV ratings
Custom requirements
Locations
Delivery needs
We can then provide competitive pricing and help you compare:
Product cost | Custom capabilities | Lead times | Inventory | Freight | Delivery | Overall service
There's no need to rebuild your filtration program before talking to us.
Send us what you're buying today and let us take it from there.
Custom Size Air Filter Supplier Comparison
What to Evaluate | Typical Filter Distributor | Airex Filter |
Standard HVAC filters | Usually | Yes |
Custom size filters | May be outsourced | Manufactured by Airex |
New England manufacturing | Varies | Hudson, New Hampshire |
Local inventory | Varies | Extensive inventory |
Greater Boston delivery | Carrier dependent | Regular Airex delivery service |
Standard + custom requirements | Varies | Yes |
Commercial & industrial focus | Varies | Yes |
Multi-location support | Varies | Yes |
50+ years in filtration | Varies | Yes |
Family-owned business | Varies | Yes |
Send Us Your Filter List — We'll Help From There
Facilities teams don't need to spend hours reorganizing a filter schedule just to request pricing.
If you already have a:
Spreadsheet
Filter schedule
Previous purchase order
Current supplier quote
List of sizes and quantities
send it to Airex.
Our team can review the information, identify standard and custom requirements, and work with you to build a quote around the way your organization actually purchases filters.
Have 10 filter sizes?
Send them.
Have 200?
Send those too.
Frequently Asked Questions About Custom Size Air Filters
Can air filters be made in custom sizes?
Yes. Commercial HVAC filters can be manufactured in many non-standard and fractional dimensions. Custom filters are commonly used in older HVAC systems, specialty equipment, commercial buildings, industrial facilities, and applications where a standard nominal size does not properly fit the existing filter rack.
Does Airex manufacture custom size air filters?
Yes. Airex Filter Corporation manufactures custom size HVAC air filters in Hudson, New Hampshire for commercial and industrial applications.
How do I measure a custom air filter?
Measure the filter's actual length, width, and depth. Be careful not to assume that the dimensions printed on an existing filter represent its exact physical measurements because many HVAC filters are identified using nominal dimensions.
If you're uncertain, confirm the measurements before placing a large custom order.
What is the difference between nominal and actual air filter size?
Nominal size is the commonly referenced filter dimension. Actual size is the filter's physical measurement.
For example, a filter sold using a nominal dimension may be manufactured slightly smaller, so it properly fits the intended HVAC equipment.
Are custom air filters available in different MERV ratings?
Yes. Depending on filter type, construction, dimensions, and application, custom filters can be produced in multiple efficiency levels.
The appropriate filtration efficiency should be selected based on the HVAC system and facility requirements.
How long do custom air filters take to manufacture?
Lead times depend on the product, dimensions, quantity, production schedule, and manufacturer.
Facilities that regularly use custom filters should discuss anticipated lead times with their supplier and consider planning recurring requirements ahead of scheduled filter changes.
Can Airex supply standard and custom air filters together?
Yes. Airex combines custom manufacturing with a broad selection of standard commercial and industrial filtration products, helping facilities consolidate more of their filtration requirements with one supplier.
Can Airex quote a large facility filter schedule?
Yes.
If you already have a spreadsheet containing sizes, quantities, MERV ratings, filter types, or building information, send it to Airex.
Our team can review the schedule rather than requiring you to submit every filter individually.
Can Airex support multiple facilities?
Yes. Airex works with commercial and industrial organizations that manage filtration requirements across multiple buildings and locations.
Does Airex deliver air filters in Boston?
Yes. Airex has a strong presence in the Greater Boston market and provides regular delivery service into Boston as part of its New England distribution operation.
Where is Airex Filter located?
Airex Filter Corporation is headquartered and manufactures air filtration products in Hudson, New Hampshire.
Can a supplier stock custom filters for my facility?
Depending on the supplier and purchasing program, frequently ordered custom sizes may be manufactured or planned in advance to help reduce replenishment time.
Facilities with predictable usage should discuss inventory and scheduled purchasing options with their supplier.
Should I use one supplier for standard and custom air filters?
When the supplier has the necessary product range and manufacturing capability, consolidating standard and custom filtration can simplify purchasing, shipping, inventory management, invoicing, and account administration.
What should I send Airex to get a custom filter quote?
Send the filter dimensions, quantities, filter types, and MERV ratings when available.
For larger requirements, the easiest option is often to send Airex your existing filter spreadsheet, schedule, previous purchase order, or current purchasing list.
What should I look for in a custom air filter supplier?
Facilities should evaluate more than price.
Consider custom manufacturing capability, proper sizing, filtration performance, lead times, inventory, product availability, delivery, communication, ability to support multiple locations, and the overall cost of managing the supplier.
Looking for a Better Custom Air Filter Supplier?
Whether you're managing one commercial building or an entire portfolio, Airex Filter can help simplify your filtration program.
Custom sizes. Standard sizes. Commercial and industrial filtration. Extensive inventory. New Hampshire manufacturing. Reliable New England delivery.
Already know what you need?
Send us the list.
Not completely sure?
Send us what you have.
We'll help from there.
Airex Filter Corporation
Hudson, New Hampshire
800-660-2298
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