24x25x5 MERV Ratings Day and Night Air Filters Buyer Guide
TL;DR: A Day and Night 24x25x5 air filter is a 5-inch-class pleated filter that actually measures 23.63 x 24.69 x 4.25 inches. MERV 8 handles dust, and MERV 11 adds pollen and dander capture. MERV 13 goes further, trapping smoke-sized particles.
I write about air ionizers, and readers often ask which furnace filter to pair with one. For a Day and Night 24x25x5 cabinet, my answer is MERV 11 for most homes.
Key Takeaways
Nominal sizes do not round one way: a Day and Night 24x25x5 runs smaller than its label (23.63 x 24.69 x 4.25 inches), while a 20x20x5 runs larger, so order from actual dimensions.
MERV 13 must catch 50% of 0.3 to 1.0 micron particles; MERV 8 has no requirement there.
MERV 11 suits most homes; MERV 13 is the upgrade for asthma, smoke, or Saharan dust.
All three ratings cost the same per filter, so choose based on air quality and airflow, not price.
Replace every 90 days at most; sooner with pets, allergies, or asthma.
What Size Is a Day and Night 24x25x5 Air Filter, Really?
A Day and Night 24x25x5 filter actually measures 23.63 x 24.69 x 4.25 inches; 24x25x5 is the rounded, nominal size. Filterbuy, an air filter manufacturer that makes its pleated HVAC filters in the USA, sells this replacement in MERV 8, 11, and 13.
What surprised me when I lined up Day and Night listings: sizes do not round one way. The Day and Night 20x20x5 filter, also sold for Canadian homes, measures 20.25 x 20.75 x 5.25 inches, larger than its label and a full inch deeper than the 24x25x5. A 20x25x5 replacement made for Honeywell media cabinets follows another spec, and even a 16x25x1 pleated filter lists its actual size as 15.50 x 24.50 x 0.75 inches.
For other sizes, see guides to standard HVAC air conditioner filter sizes and to 16x22x1, 20x24x1, 16.5x22x2, and 16x20x4 filters.
Day and Night, an International Comfort Products (ICP) brand under Carrier, pairs many systems with a 24 x 25 return-side media cabinet that takes this deep pleated air filter.
All three ratings fit the same slot, so fit causes more avoidable mistakes than rating. The National Air Filtration Association calls it air filter bypass: air that slips around the edges never touches the media, even on a high-MERV filter.
How Do MERV 8, MERV 11, and MERV 13 Compare?
The difference between MERV 8, 11, and 13 is how small a particle each reliably catches. All three are scored under the ASHRAE 52.2 test standard.
MERV 8: Dependable Everyday Filtration
MERV 8 is the baseline for protecting the blower and coil. Per the EPA's summary of the standard, it captures at least 70% of particles from 3 to 10 microns and 20% from 1 to 3 microns. To me, the MPR and FPR equivalents are the most useful line on a listing. Filterbuy maps MERV 8 to MPR 600 and FPR 5, the same pairing printed on this 20x25x1 MERV 8 (FPR 5) filter at Home Depot.
MERV 11: The Allergy-Season Middle Ground
MERV 11 raises the minimums to 85% of 3 to 10 micron particles and 65% of 1 to 3 micron particles, catching more pollen and pet dander. It maps to MPR 1000 to 1200 and FPR 7. A review of a 20x25x5 MERV 11 filter for Day and Night systems likewise names MERV 11 the practical upgrade for 5-inch cabinets.
MERV 13: Fine-Particle Filtration
MERV 13 is the only one of the three required to catch at least 50% of particles from 0.3 to 1.0 microns, along with 85% from 1 to 3 microns and 90% from 3 to 10 microns. That smallest band includes smoke and many bacteria. It maps to MPR 1500 to 1900 and FPR 10.
Filterbuy's Day and Night 24x25x5 listing rates MERV 8 at 90%, MERV 11 at 95%, and MERV 13 at 98% of airborne particles, without stating the test method. I read those numbers as a ranking of the three options, and the EPA chart as the guaranteed floor.
Which MERV Rating Is Best for Your Home?
MERV 11 is the best fit for most homes. That mirrors this explainer on whether HVAC filters improve air quality or just protect your furnace, which treats MERV 8 as a baseline and MERV 11 as the default.
Choose MERV 8 if the house has no allergy sufferers or pets and you change filters on schedule.
Choose MERV 11 if you share the house with a dog or cat (see these tips for removing pet dander when you have allergies), seasonal pollen bothers someone, or windows stay open part of the year.
Choose MERV 13 if someone has asthma, smoke or heavy dust reaches your area (the EPA's wildfire smoke guidance recommends MERV 13), or you want maximum fine-particle capture.
For South Florida, we lean one step higher: AC rarely rests, and summer Saharan dust plumes that reach Florida each year plus a long pollen season load filters fast. During a dust or smoke advisory, I set the fan to "On" instead of "Auto" so air keeps moving through the filter, as the EPA's wildfire guidance suggests, and check the filter afterward.
Will MERV 13 Restrict Airflow in a Day and Night System?
Usually not in a 5-inch cabinet. ASHRAE notes that higher efficiency increases pressure drop, but a 4.25-inch filter spreads that resistance across far more media than a 1-inch filter, such as a 16x25x1 MERV 8 pleated filter.
My rule of thumb: if a room starts lagging after an upgrade, suspect the filter first and the ducts second; leaky ductwork causes the same symptoms, and duct repair is sometimes the fix. Drop back one rating and have a licensed HVAC technician measure static pressure; Florida homeowners can confirm a license through the DBPR license search.
How Often Should You Replace a 24x25x5 Filter?
Filterbuy recommends replacement every 90 days, every six weeks with asthma or allergies, and every two months with pets. The EPA's guide to air cleaners in the home adds that heavily soiled filters need changing sooner. With South Florida run times, I treat 90 days as a ceiling, not a target.
ENERGY STAR suggests monthly checks, and pet and allergy homes need shorter intervals with any thick filter, per this guide to changing a 4-inch furnace filter in winter. A filter won't add moisture, though: dry winter air calls for a humidifier, not a different filter.
What Does a 24x25x5 Filter Cost per Month?
A Day and Night 24x25x5 filter costs roughly $15 a month on a 90-day schedule, or about $32 a month on the six-week allergy schedule. Nobody prints this on the box, so I did the math. Filterbuy prices all three MERV levels the same: $84.99 for one filter, or $43.99 each in packs of four or more.
Swap-Day Checklist for a Day and Night Media Cabinet
Five steps keep a new 24x25x5 sealed and working.
Turn the system off at the thermostat.
Photograph the old filter's label so the actual size is on your phone.
Vacuum the cabinet track so debris can't break the seal.
Point the airflow arrow toward the furnace or air handler, away from the return duct.
Latch the access door fully and date the frame.
Do You Still Need a Good Filter If You Have an Air Ionizer?
Yes, an ionizer still needs a good filter, and readers here ask about this pairing often. Ionizers make particles clump or settle; the filter is what pulls them out of circulating air, as covered in how the right furnace filter boosts air ionizer performance. EPA-cited tests found ionizers removed dust, smoke, pollen, and spores less effectively than high-efficiency filters. My take: an ionizer without a good filter can end up moving dust from the air onto your furniture.
Before an in-duct ionizer goes in, ask about UL 2998 zero ozone emissions validation, since the EPA warns against air cleaners that intentionally produce ozone. Palm Beach County homeowners can compare local air ionizer installation options.
"The first thing I tell readers to check is the depth printed on the old frame, not the box label. Two filters sold as 5-inch can differ by a full inch."
-Kathe Menze, author
Essential Resources
24x25x5 replacement air filters for Day and Night media cabinets: This product page lists actual dimensions and replacement intervals for all three MERV options.
What Is a MERV Rating? The EPA charts the minimum capture each MERV rating must reach by particle size.
Filtration and Disinfection FAQ: ASHRAE explains its MERV 13 recommendation and the pressure drop tradeoff.
Heating and Cooling Maintenance Checklist: ENERGY STAR recommends monthly filter checks to protect equipment and energy bills.
Basics of Air Filtration: The National Air Filtration Association's videos explain air filter bypass around loose filters.
Indoor Air Quality and Indoor Air Pollution: Allergy & Asthma Network outlines how allergy and asthma households can cut indoor triggers.
Air Filter Buying Guide: Consumer Reports explains why thick filters handle high MERV ratings better than restrictive 1-inch filters.
Supporting Statistics
About 44% of Americans (152.3 million people) live where ozone or particle pollution earned a failing grade in the 2026 State of the Air report.
Source: American Lung Association, State of the Air Key Findings
Nearly 28 million people in the U.S. have asthma, about 8% of the population.
Source: Asthma and Allergy Foundation of America, Asthma Facts
Nearly 1 in 3 U.S. adults and more than 1 in 4 U.S. children reported having a seasonal allergy.
Source: American College of Allergy, Asthma and Immunology, Allergy Facts
Final Thoughts
Fit and timing matter as much as the rating. A well-seated MERV 11 changed on schedule will usually do more for your air than a loose or overdue MERV 13.
Next Steps
Confirm the actual size on your current filter frame.
Pick MERV 8, 11, or 13 and set a replacement reminder.
Add dryer vent cleaning to your calendar and compare dryer vent cleaning companies near you.
Frequently Asked Questions
Is MERV 13 Too High for a Residential Furnace?
Not usually. In a 5-inch Day and Night media cabinet, deep pleats keep MERV 13 resistance manageable, though older or undersized blowers can struggle.
Can I Use a 24x25x4 Filter Instead of a 24x25x5?
No. A 4-inch-class filter is shallower and leaves a gap in a 5-inch cabinet track, letting air bypass the media.
Does a Higher MERV Filter Raise Energy Bills?
Only modestly in a 5-inch cabinet; a clogged filter at any rating raises energy use more than a clean MERV 13.
Can I Wash and Reuse a 24x25x5 Pleated Filter?
No. A disposable pleated 24x25x5 filter is not washable; water damages the media.
Choose the Right MERV for Your Day and Night 24x25x5 Filter
The right MERV rating for your household is the simplest upgrade a Day and Night media cabinet allows. Measure the old filter before you choose, then put the next swap on your calendar.
Glossary
MERV (Minimum Efficiency Reporting Value): A 1 to 16 ASHRAE 52.2 rating of how well a filter captures 0.3 to 10 micron particles.
Nominal vs. actual size: Label size versus measured size.
Pressure drop: The airflow resistance a filter adds, rising with MERV rating and dust load.
Day and Night 24x25x5 air filter: A 5-inch-class pleated filter for Day and Night media cabinets, made in the USA by Filterbuy at 23.63 x 24.69 x 4.25 inches in MERV 8, 11, and 13.
Learn more about HVAC Care from one of our HVAC solutions branches…
Filterbuy HVAC Solutions - Miami FL - Air Conditioning Service
1300 S Miami Ave Apt 4806 Miami FL 33130
(305) 306-5027
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