Order your custom air filter here
Why custom air filters from filterbuy?
At filterbuy, we always have your size. Watch the video to learn more.
Most Orders Ship in 24 HoursProudly Custom Made in the USA85,000+ 5-Star Reviews
TL;DR
Most homes take one of the 600+ sizes Filterbuy stocks, so start there. If yours isn’t on the list, we’ll cut a custom filter to the size you measure, to the eighth of an inch, in MERV 8, MERV 11, MERV 13, or Odor Eliminator. Order length and width by what you actually measured rather than the rounded number on the frame, and round depth to the nearest inch.
Key Takeaways
Check Filterbuy’s 600+ standard sizes first. Custom is the fallback for when yours isn’t there.
Filterbuy cuts, pleats, and frames custom filters to order in its own US plants, to the eighth of an inch.
Custom filters can’t be returned unless there’s a manufacturing defect, so it’s worth measuring twice.
Build Your Custom Air Filter Online
Enter your width, length, and depth below, pick a MERV rating, then choose a one-time order or auto-delivery. Filterbuy cuts custom air filters for furnaces, air conditioners, heat pumps, and any HVAC system with a return that isn’t a stocked size. Your price shows up as soon as your dimensions are in.
What Size Custom Air Filter Do I Need?
Order length and width by actual size, meaning the number your tape measure gives you and not the rounded figure on the frame. Depth is the exception. Round it to the nearest inch, since that’s the one dimension Filterbuy builds to a set thickness. Length and width we cut to within an eighth of an inch.
Here’s what trips people up. A filter labeled 20x25x1 doesn’t measure 20 by 25 by 1. A Filterbuy 20x25x1 comes off the line at 19.50 x 24.50 x 0.75, undercut on purpose so it slides in without binding.
Our air filter sizes chart lists nominal against actual for every size we cut.
Turn the system off at the thermostat before you pull anything out.
Slide the old filter out and note which way its airflow arrow points. The new one goes in the same direction.
Measure the old filter’s length and width edge to edge, to the nearest eighth of an inch. If there isn’t a filter in the slot, measure the opening.
Measure the depth and round it to the nearest inch.
Enter all three numbers in the builder above.
Nominal Size vs. Actual Size, and Why Custom Flips the Rule
Nominal size is the rounded number printed in large type on a filter frame, something like 20x25x1. That’s the name you order by. Actual size is what the filter measures in your hands, and it’s smaller by design, because the clearance is what lets the filter slide into the slot. Standard filters go by the nominal number, while a Filterbuy custom filter takes the actual length and width you supply.
Depth runs 0.75 on a 1-inch, 1.75 on a 2-inch, and 3.63 on a 4-inch.
Undercuts vary between manufacturers, so read the actual size on a frame before you switch brands.
When Should You Order a Custom Air Filter Instead of a Standard Size?
Order a Filterbuy custom air filter when your size isn’t on the standard list. That’s usually a whole-inch size off the common list, like 13x21x1 or 17x19x1, a half-inch or quarter-inch actual, such as 19.5x21.5x1, or an older system with a return built to its own spec. If a standard filter rattles in the slot or has to be forced, it’s the wrong size.
If your slot comes within about a quarter inch of a standard size, a standard filter will usually seal fine and cost less. Past that, custom is the better answer. Start with Filterbuy’s 600 standard sizes.
Is a Custom Filter Better Than Cutting Down a Standard One?
Cutting a standard filter down to fit breaks the seal its frame is meant to make, and once that seal’s gone, unfiltered air slips around the media instead of through it. A filter rattling in an oversized slot does the same. Either way the dust ends up in your blower and coil. A Filterbuy custom filter sized to the slot keeps that seal intact.
Here’s the quick check. A correct fit slides in with light friction. If you have to force it, it’s too big, and if it rattles when you close the access door, it’s too small.
H2 Which MERV Rating Should You Choose?
Filterbuy makes custom air filters in four grades, rated on MERV, the industry scale for how much a filter captures. MERV 8 captures 90% of airborne particles, and it’s the standard choice for most homes. Step up and MERV 11 captures 95% of airborne particles, MERV 13 captures 98% of airborne particles. Odor Eliminator uses carbon media for household odors.
Whichever grade you pick, check your HVAC manual to confirm what your system takes, the same way you’d confirm a size.
MPR and FPR are third-party rating systems from other companies, shown for comparison only.
The EPA recommends a filter rated at least MERV 13, or as high as your system will accommodate. All four grades come in the custom sizes we cut, so your size doesn’t limit the grade you choose.
How Long Does a Custom Air Filter Take to Arrive?
Fast, free 2-day delivery to most US states. Custom sizes usually sit in a queue somewhere, which is why much of the industry quotes ten business days or more. Filterbuy cuts, pleats, and frames custom filters to order in its own US plants, on the same lines as our standard sizes, so a custom order doesn’t wait for a batch.
If you’ve been searching for custom-made air filters near me, Filterbuy is a manufacturer, and yours gets cut to order in our own US plants.
Before You Order, Check These Three Things
Filterbuy custom air filters can’t be returned, so two minutes here is worth spending. Measure the old filter first, and if there isn’t one in the slot, measure the opening instead. Enter length and width exactly as you measured them, and round depth to the nearest inch.
If your tape and the printed frame disagree, go with the tape.
How Filterbuy Builds a Custom Filter
Filterbuy cuts, pleats, and frames its filters to order in its own US plants, and two details follow from that. The undercut on our standard sizes is our own convention, so another maker’s 20x25x1 may not measure what ours does. And because we cut custom filters down from larger stock, the frame you receive may still carry the label of the size it started as.
Supporting Statistics
Two federal findings put the case for clean filtration in plain numbers. Both come from US government sources, and both are worth knowing before you decide how often to change a filter.
Americans spend approximately 90 percent of their time indoors, where concentrations of some pollutants are often 2 to 5 times higher than typical outdoor concentrations.
U.S. Environmental Protection Agency, Report on the Environment: Indoor Air Quality
The air your HVAC system moves is the air you breathe for most of the day.
Routinely replacing or cleaning your air filters can lower an air conditioner’s energy consumption by 5 to 15 percent.
U.S. Department of Energy, Energy Saver 101: Home Cooling
That’s the case for auto-delivery: a filter you replace on schedule is doing the job you paid for.
I don’t want anyone to feel like they need an HVAC license just to pick the right filter. My job is to give you the straight answer, explain why it matters, and let you get back to your day.
Michelle Wan, Brand Manager and Air Quality Writer at Filterbuy
How Much Do Custom Air Filters Cost?
Custom air filter pricing at Filterbuy comes down to size, MERV rating, and quantity, and it shows up in the builder as soon as your dimensions are in. A custom filter costs more than a stocked size, since we cut and assemble each one on its own. Auto-delivery takes another 5% off.
Can I Set Up Automatic Replacement?
Pick auto-delivery in the builder and choose your interval. Your custom size is saved, so you don’t have to measure again. Filterbuy suggests changing a 1-inch filter about every 90 days, sooner in a house with pets. It works like an air filter subscription: replacements arrive when it’s time, at 5% off.
Can I Return a Custom Air Filter?
Filterbuy custom air filters aren’t eligible for return or refund, except in cases of a manufacturing defect, because each one’s cut to dimensions only you supplied. Call (855) 345-8289 for a second set of eyes on your numbers first. Our returns policy covers standard sizes, which are eligible for a 90-day exchange
Filterbuy Custom Air Filter FAQ
Should I Order by Nominal or Actual Size?
Order length and width by actual size, the number you measured. Depth rounds to the nearest inch.
What If My Measurement Falls Between Two Sizes?
Don’t round length or width. Enter what you measured, and Filterbuy cuts to within an eighth of an inch.
Are Filterbuy Custom Air Filters Made in the USA?
Yes. Custom filters are cut, pleated, and framed to order in Filterbuy’s own US plants. We manufacture what we sell.
Is There a Size Too Large for a Custom Filter?
Over 29.81 inches on both sides, or 35.81 on one side, we build a double filter: two panels fused at a center seam, shipped assembled.
Which MERV Rating Do Most People Order?
MERV 8 is the standard choice for most homes. Check your HVAC manual to confirm what your system takes.
Glossary
Nominal and actual size: Nominal is the rounded number on the frame and the name you order by. Actual is what a filter measures: a Filterbuy 20x25x1 is 19.50 x 24.50 x 0.75 inches.
MERV: Minimum Efficiency Reporting Value, the industry scale for how much a filter captures. See MERV ratings explained.
MPR and FPR: Third-party rating systems from other companies, shown for comparison only. See MERV, MPR, and FPR compared.
Bypass: Air that escapes at the frame and travels around a filter, missing the media.
Related: air filter sizes chart · how to measure your air filter · MERV 8 air filters · MERV 11 air filters · MERV 13 air filters · odor eliminator air filters · air filter subscription
