You pull a gray filter out of your return grille and look at the cardboard edge for the size. The frame shows 11.5x24.5x1.75 next to a larger number, and both numbers are correct. You need a 12x25x2 air filter MERV 11 to fit that slot, and we stock this exact size in three grades. The printed size and the measured size are two different numbers. The grade decision comes after the size match. You match the new box to the old frame, and the rest of this guide gives you the grade. You need to know how to read the frame to get the right match, and that takes one minute with the old filter in your hand.
The frame shows two sizes and both are correct
The nominal size prints on the cardboard frame edge of the old filter. Order by that printed number. A tape measure across the frame gives the actual size, and that measured number is a half inch under on both faces and a quarter inch under on depth. That undersize is what lets the frame slide into the slot. A filter that measures a full 12 by 25 by 2 inches binds against the metal grille. Ordering by the tape number gets the wrong filter. The wrong filter falls out of the tracks or leaves gaps for air to bypass the media, and bypass air carries dust straight into your blower. The factory prints the nominal dimensions to match the housing label, so the printed number on the old frame and the printed number on the new box agree. You prevent bypass air when you trust the printed nominal size. Our guide to reading the size on any air filter explains this common difference.
Three grades and one price table
We stock the 12x25x2 pleated air filter in three grades, and we sell each grade as a box of six. The filters are pleated and electrostatically charged, and the charge helps the pleats hold airborne particles. The spread from MERV 8 to MERV 13 is $46.00 a box. The step from MERV 11 to MERV 13 is $21.00 a box.
| Grade | Box of six | Per filter | Captures |
|---|---|---|---|
| MERV 8 | $59.99 | $10.00 | Dust, lint and pollen |
| MERV 11 | $84.99 | $14.17 | Adds pet dander and finer dust |
| MERV 13 | $105.99 | $17.67 | Adds smoke and fine particles |
The MERV 8 option works out to $10.00 per filter. A box of the 12x25x2 MERV 11 Pleated Air Filter 6PK costs $84.99, which comes to $14.17 per filter. The highest grade is $105.99 a box, or $17.67 per filter. The price rises as the filter captures smaller particles. You pick the grade that matches what you want out of the air, and you pick the price that matches your maintenance budget. The whole grade sits in our MERV 11 Air Filters collection. We arrange the store by size and grade so the match takes a minute.
MERV 11 or MERV 13 on a two inch slot
MERV stands for Minimum Efficiency Reporting Value. The ASHRAE 52.2 test behind it measures what share of particles in each size range a filter captures. MERV 8 handles dust, lint and pollen. MERV 11 adds pet dander and finer dust, and MERV 13 adds smoke and fine particles. Our guide on MERV 11 and MERV 13 notes that MERV 11 captures about 20 percent of particles between 0.3 and 1 micron, and that MERV 13 captures at least 50 percent of that range. Smoke and the fine droplets that carry germs fall in that band. That gap is what the $21.00 buys.
Every higher grade costs some airflow, because tighter media puts more resistance in the path of the blower, and the blower works harder to pull air through it. A two inch pleat has more media face than a one inch pleat, so the two inch filter carries a higher grade with less resistance than a one inch filter of the same grade. Your furnace or air handler manual lists the filter resistance the blower is rated for. Read that manual before you move to the highest grade. Our MERV 11 media is changing to blue, and the change rolls out as existing stock ships first. The quality of the media does not change.
How to change a 12x25x2 filter
- Turn the system off at the thermostat.
- Note the direction of the airflow arrow on the old frame.
- Pull the old filter straight out of the slot.
- Read the frame to confirm the nominal size is 12x25x2.
- Slide the new filter in with the arrow pointing toward the blower.
- Write the date on the new frame with a marker.
Every pleated filter frame prints an arrow, and the arrow points toward the blower, which is the direction the air flows. The system pulls air from the room into the return duct, through the filter media, and into the blower. A filter installed backward puts the air pressure against the weaker side of the pleats, and the pleats can collapse into the duct under that load. You avoid that problem when you match the arrow to the air path. Write the install date on the frame while the filter is still in your hand, because the date is what tells you the interval a year from now.
How often a two inch pleat needs changing
We publish no replacement interval for air filters. The equipment manufacturer sets the schedule in the manual. General practice puts a two inch pleated filter on a 60 to 90 day change, and your own schedule depends on your house. Pets and pollen season shorten the life of a filter. Smoke and remodeling dust fill the pleats faster still. A dark gray media face means the filter is full, and a full filter forces the blower to pull against a blocked sheet of material. The system then runs longer cycles to heat or cool the house, and the longer cycles use more energy. You avoid that strain when you replace the filter on time. You swap the filter early when the pleats look packed, even when the calendar says you have weeks left. Write the date on the frame at each change, and you learn your own interval within a year.
Set the reorder on Subscribe and Save
A clean filter needs a new box in the closet before the old one loads up. Our Subscribe and Save program sends that box on a schedule of three months, six months or a year. The program applies a standing 5 percent discount to every recurring shipment. On the MERV 11 box of six, 5 percent off the $84.99 price is $80.74. You keep that discount for as long as the plan stays active, and you get the discount and the regular delivery in one step. The fresh box arrives before the return needs it, and the remaining five filters wait in a dry closet for the next change. The automatic shipment saves you the trip to the store, and we ship the exact size you selected the first time. You can pause a shipment or change the interval from your account.
Frequently Asked Questions
Is a 12x25x2 filter the same as 11.5x24.5x1.75?
Yes. The two numbers describe the same filter. The larger number is the nominal size you order by, and the smaller number is the actual size measured across the frame. Every 12x25x2 filter we sell measures 11.5 x 24.5 x 1.75 inches, and both sets of dimensions print on the cardboard edge.
How do I choose a MERV grade for a 12x25x2 return?
Base the grade on what your blower handles and what you want to capture. A 12x25x2 air filter MERV 8 is the common starting point for dust and pollen. MERV 11 adds pet dander and finer dust, and it balances capture against airflow for most houses. Check your system manual to confirm the blower accepts the resistance of a higher grade before you step up. Watch your indoor air over a month with the new grade in place, and step up again only when the manual allows it.
Can I put a MERV 13 in a slot that came with MERV 8?
You can make that switch when the manual approves the filter resistance. A 12x25x2 air filter MERV 13 has denser media to capture smaller particles, and that density costs some airflow. A two inch pleat handles that resistance better than a one inch pleat, because the deep folds spread the air over a wider surface. Your system manual has the final word on approved resistance.
How many filters come in the box?
We sell this size in a box of six, and you receive six identical pleated filters in the grade you select. Six filters cover a full year on a 60 day change. Store the remaining filters in the box, in a dry closet, until you need them.
Order the right match today
We are Poseidon Filters. We sell the filters, and we do not service furnaces or air handlers. Order the 12x25x2 MERV 11 Pleated Air Filter 6PK to capture pet dander and finer dust, or pick MERV 8 or MERV 13 in the same size. We ship the box to your door, and you slide the fresh filter into the slot. Call us at 855-789-3278 if you want us to confirm the match. We answer the phone Monday to Friday, 9 to 3 Central, and you can email info@poseidonfilters.com with the size off your frame.
Reviewed by the filtration specialists at Poseidon Filters, who match residential and office systems to the correct filter sizes every day.