Custom Size NaturalAire MERV 8 Filters (12 Filters)

Min. Size: 6" x 6" - Max. Size: 25" x 30". Contact support if you need a filter with a length or width greater than 30".

Sale price$ 208.99

🚚 Estimated Delivery: Please allow 2-10 business days for standard delivery

✅ Filter Fit Guarantee

✅ Free Standard Delivery


Filter Specifications

MERV Rating: MERV 8

Media: Electrostatically charged pleated media helps keep your air and HVAC system clean for more efficient operation, saving you money on energy consumption and equipment repairs.

Frame: Heavy-duty, two piece, moisture-resistant frame with diagonal support members. Frame is bonded to the media at all points of contact for unsurpassed frame strength. Interlocking corners and positive media-to-frame seal reduce the possibility of air bypass.

Support Grid: Expanded metal is continuously laminated on the air leaving side to provide pleat stability during operation. Pleat shape is maintained allowing full media utilization which improves dust holding capacity.

Replace: Recommended 90 day changeout

Removes: MERV 8 rating reduces up to 75% of large airborne particles including dust and lint, dust mite debris, pollen, pet dander, mold spores, bacteria and virus carriers.

Quantity: 12 Filters

Part Number: C-84858

Custom Size: Filters will be manufactured to the exact size submitted with order. Purchase protected by no-worry filter fit guarantee.

Millions of Filters Sold and Replaced

Thank you to our valued customers for 16+ years in business. RTF is a trusted retailer for leading brands in the indoor air filtration industry. We strive to provide the best service and air filtration products for our valued customers.

Custom Size Replacement Air Filters

A well-fit air filter not only improves air quality in your home or business, but it can also extend the life of your equipment. We enforce high standards, top craftsmanship, and consistent quality. A high-quality filter can keep you and your family breathing cleaner, healthier indoor air.

Compatible with Furnace, AC and HVAC Systems

The terms furnace filter and air conditioner (AC) filter. Are there really two different filters for the heating, ventilation, and air conditioning (HVAC) system in your home, or are they referring to the same filter? The answer—they are the same! Often times it depends on what part of the county you are in for the term you hear more often.

Homeowners & Single Filters

Don't Let Anything Past Your Filter

Airflow will always take the path of least resistance, this holds true with the air in an HVAC system in homes and businesses. Simply put air is lazy so it wants to find the easiest way out. If you have gaps between your filter and the storage rack in your system even if minor you can bet that is where the air wants to go. This allows unfiltered air to make it back into your home or business, and since that unfiltered air is also traveling through your HAVC system it could lead to costly repairs.

No Worry Filter Fit Guarantee

At, we want to make you happy. That’s why we work hard to ensure you’re always 100% completely satisfied with your purchase. And why we have not just one but two guarantees to make sure if you – or we – make a mistake on an order, we’ll do everything possible to make it right!

Learn More about the Filter Fit Guarantee

Improve energy efficiency

Improve Energy Efficiency

Save on energy costs and maintenance fees. Replacing your air filters can also improve the lifespan of your HVAC system. Quality filters will capture particles from the air you breathe but also allow air to travel freely through the filter reducing operating costs.

Frequently Asked Questions

Please enter the exact filter size you need your custom filters to be made in 1/8" increments.

Example: 14-3/8 x 26-1/2 x 1

Increments accepted: 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8, 1.

Conversion Chart

  • 1/8 = .125
  • 1/4 = .25
  • 3/8 = .375
  • 1/2 = .5
  • 5/8 = .625
  • 3/4 = .75
  • 7/8 = .875

Minimum Size: 6" x 6" - Maximum Size: 25" x 30"

If you need a larger filter size let us know. We can make larger filters but will need to quote based on your filter size.

Contact support if you need a larger size or assistance.

Furnace, AC and HVAC filters are most often measured in inches. A nominal measurement would be a rounded number like 20x25x1, rounded up to the nearest inch. These filters if measured with a tape measure would likely be closer to 19 ½" x 24 ½" x ¾" which would be the actual true exact size. When ordering custom filters enter the actual true exact size you need your filters to be made.

Choosing the correctly sized air filter is important in order to keep air clean in your home. An improperly sized filter may have limited performance. Determining the proper air filter size can be confusing, since filter packages generally display two sets of dimensions. It is important to understand that these dimension sets are the nominal and actual dimensions of the filter, and differences between the two.

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Depending on the filter model most 1" depth filters are going to have an actual depth between 3/4"-7/8".

For 2" filters the depth will be 1-5/8". Not all filter models are available in 2" depth. If the 2" option is available there will be a dropdown to select the depth. Otherwise filters will be made in 1" depth.

If you have any questions or concerns please let us know.

We get it. Measuring your own HVAC system for custom furnace and AC filters can seem a little scary. But fear not! The team is here to help you succeed! And if you make a mistake, no worries. With our Filter Fit Guarantee, you can’t go wrong!

More Information

At, we want to make you happy. That’s why we work hard to ensure you’re always 100% completely satisfied with your purchase so you never have to return it. However, in the unlikely event you need to, we’re ready to make it right! For more information on the return policy please visit the "Returns" page.

Minimum Efficiency Reporting Value (MERV) is a filter industry standard system that rates the overall effectiveness of air filters. Higher value MERV rating equates to finer filtration, meaning fewer dust particles and other airborne contaminants can pass through the filter. Other common ratings found within certain brands and stores includes FPR, MPR. They all follow the same basic principal, the higher the number the greater overall effectiveness of the air filter.

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Most often there will be an arrow on the side of the filter which will indicate which way to insert the filter. The arrow will show which direction the air is to travel through the filter. If there is no arrow the filter can be installed in both directions. 

Remember your filter is designed to protect your system first and foremost. Air should be traveling through the filter before your blower and system.

Please allow 5-10 business days for most custom filter orders to be manufactured. Once your filters are made it will take 1-5 business days for your filters to be delivered by our shipping partners. All filter orders ship for free out of the production plant nearest you; FL, NY, OK, IL, CA, NC or WA. Current production times can be found on our lead time page. Delivery details will be provided in your confirmation email.

All filter orders ship for free in the domestic US. Free shipping is available for addresses inside the 48 contiguous states only. Give us a call at 866-469-8556 or send customer service a quick email if you have questions.

Customer Support


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