Tip: Ensure you buy the exact air filter size for your system. Certain brands have precise dimensions that only fit their specific models. See related filters
21x24x4.5 MERV 13 Replacement Filter Ruud RXHF-E24AM10, RXHF-E24AM13
Actual Size: 20.63x24.13x4.38
Free Delivery 
Factory-Direct Low Prices, Made in the USA
Hassle-Free Returns & Free Exchanges
RESIDENTIAL AND/OR COMMERCIAL USE
Change Every 3 Months
Tip: Ensure you buy the exact air filter size for your system. Certain brands have precise dimensions that only fit their specific models. See related filters
21x24x4.5 MERV 13 Replacement Filter Ruud RXHF-E24AM10, RXHF-E24AM13
Actual Size: 20.63x24.13x4.38
Free Delivery Factory-Direct Low Prices, Made in the USAHassle-Free Returns & Free ExchangesRESIDENTIAL AND/OR COMMERCIAL USE
Change Every 3 Months
Tip: Ensure you buy the exact air filter size for your system. Certain brands have precise dimensions that only fit their specific models. See related filters
21x24x4.5 MERV 13 Replacement Filter Ruud RXHF-E24AM10, RXHF-E24AM13
Actual Size: 20.63x24.13x4.38
Free Delivery Factory-Direct Low Prices, Made in the USAHassle-Free Returns & Free ExchangesRESIDENTIAL AND/OR COMMERCIAL USE
Change Every 3 Months
About
- This is a list 21X24.5X5 MERV 13 air filter replacement for your furnace, air conditioner, heat pump, or HVAC system
- Actual air filter size: 20.63x24.13x4.38
- MERV 13 synthetic media (comparable with MPR 1500/1900 and FPR 10) offers the best protection from dust, pollen, pet dander, mold, smog, bacteria, and virus carrying particles by trapping 98% of airborne particles without impacting air flow.
- High-quality construction means electrostatically charged pleated filter media, reinforced wire backing for structural integrity, and a durable frame to resist heat and humidity
- Built to last 3 months. 300% longer than fiberglass models
- 100% manufactured in the United States and designed with recyclable materials
- Learn more about 21X24.5X5 Air Filters
Top-Rated Filters. American Made. Delivered Free.
At Filterbuy, we don't cut corners—we craft high-quality air filters right here in the USA and ship them to your doorstep for free. No delays, no gimmicks—just clean air, made easy. With thousands of five-star reviews and filters built for real life & every HVAC system, it's no wonder why over 4 million families trust Filterbuy.
Proudly Made In The USA
Fast, Free Shipping on Every Order
Premium Materials That Go The Distance
85,000+ 5-Star Reviews From Happy Customers
Save Up to 70% Per Filter with Packs
Things to Know About Filter Sizes
Nominal Size
- The rounded size printed on your filter or HVAC unit (e.g., 21X24.5X5).
- Usually whole numbers to make identifying and ordering easier.
- A label for compatibility—not the exact measurement.
Actual Size
- The true, trimmed dimensions of the filter (e.g., 20.63x24.13x4.38 inches).
- Filters are manufactured slightly smaller so they slide into the filter slot without forcing.
- If you don't know your nominal size, measure your filter to get the actual size, then round up to find the nominal size to search on our site.
Why the difference?
- Nominal sizes simplify shopping and standardize categories.
- Actual sizes ensure the filter fits properly inside your HVAC's filter rack.
How To Find Your Nominal Size When You Don't Know It
Measure length × width × depth with a tape measure to find the actual size.
Round up each dimension to the nearest whole number to get the nominal size. Example: 20.63x24.13x4.38 in → 21X24.5X5 nominal.
Search by nominal size on our site for the best fit.
Why Getting the Right Size Matters
- Too small? Air can bypass the filter, reducing air quality and efficiency.
- Too big? It won't fit—risking bent frames and airflow issues.
- Just right? You get maximum performance, better filtration, and cleaner air.
Why Choose a 5″ filter
5″ filters give you maximum filtration with minimal maintenance — lasting up to 12 months while handling higher MERV ratings without restricting airflow.
Sizing note:
- Requires a 5″ cabinet or system.
- Actual thickness varies by brand (~4¾″–5¼″), so check your model for the best fit.
Free Exchange Policy
If the filter you buy doesn't fit, we'll send you a better size.
What's a MERV Rating?
MERV stands for Minimum Efficiency Reporting Value—but don't let the technical name fool you. It's just a way to rate how well an air filter traps stuff like dust, pollen, pet dander, and smoke. The higher the MERV number, the more particles it catches—and the cleaner your air will be.
Merv 8
Comparable to:FPR: 4-7
MPR: 600-1000
Dust & Debris
Dust Mites & Particles
Pollen
Mold
Lint
Dander
Merv 11
Comparable to:FPR: 6-9
MPR: 1200-1550
Dust & DebrisDust Mites & ParticlesPollenMoldLintDander
Smoke & Smog
Merv 13
Comparable to:FPR: 10
MPR: 1900-2800
Dust & DebrisDust Mites & ParticlesPollenMoldLintDanderSmoke & Smog
Bacteria
MERV 8
Comparable to:FPR: 4-7MPR: 600-1000
MERV 11
Comparable to:FPR: 6-9MPR: 1200-1550
MERV 13
Comparable to:FPR: 10MPR: 1900-2800
What Makes Our Filters Last 90 Days? Quality, From the Inside Out
We build every Filterbuy filter to deliver reliable 90-day performance—thanks to smart design and premium materials that do the heavy lifting. Here's what makes the difference:
Pleated Design
More pleats = more surface area to capture dust and debris, keeping your air cleaner longer.
Electrostatically Charged Media
Pleats are magnetized to attract and trap microscopic particles—like pet dander, pollen, and smoke.
Synthetic Beverage Board Frame
Engineered to resist warping in extreme temperatures and high humidity.
Aluminum Dual Wire Backing
A layer of metal reinforcement keeps pleats evenly spaced and structurally sound—no sagging, even at high airflow.
Made in the USA
Assembled with care. Built to perform. Ships fast, free, and reliably from our U.S. facilities.
How to Install Your Filter in 4 Simple Steps
Turn Off Your HVAC SystemSafety first.
Remove The Old FilterLook for the airflow arrow and make note of the direction.
Slide In Your New FilterArrow should point toward the system (same direction as before).
Turn Your System Back OnAnd enjoy the fresh, clean air.
Never forget to replace your air filter again.
- Save 5% on every order
- Choose Your Delivery Schedule
- Edit, Skip, or Cancel Anytime.
Pleated Filters vs. Fiberglass—What's the Difference?
Not all air filters are created equal. Pleated filters don't just last longer—they actually clean your air better. Here's how they stack up:
Pleated Filters
Efficiency:
High (MERV 8–13) – Traps more particles
Lifespan:
90 days – Long-lasting performance
Air Quality:
Excellent – Cleaner, healthier air
Materials:
Recyclable and durable
Fiberglass Filters
Efficiency:
Low (MERV 4 or less) – Misses small stuff
Lifespan:
30 days or less – Replace often
Air Quality:
Minimal – Basic protection only
Materials:
Thin, flimsy, and not recyclable
Pleated filters are a no-brainer—more protection, less hassle, and better air for your home.
How Often Should You Change Your Filter?
Changing your filter on time keeps your HVAC system running efficiently—and helps protect your lungs from dust, allergens, and airborne irritants. Here's how often to swap it out based on your needs:
Every 90 Days
Standard ScheduleFor most homes without pets or special air quality concerns. Great for general upkeep and energy efficiency.
Every 60 Days
If You Have Pets or AllergiesShedding fur, dander, and allergy triggers can build up fast. Changing your filter every two months helps keep the air fresher and symptoms at bay.
Every 30 Days
If You Have Respiratory Concerns or Live in Smog/Wildfire ZonesFor households affected by smoke, pollution, or respiratory conditions, monthly changes ensure maximum protection.
Want to stay on track? Set a reminder—or skip the stress with auto-delivery so fresh filters show up right when you need them.
Don't Just Take Our Word For It...
Got More Questions? We've Got Answers.
Product Specifications
| Nominal Size | 21X24.5X5 |
| Actual Size | 20.63 x 24.13 x 4.38 inches |
| Filter Type | Pleated |
| Media | Electrostatically Charged |
| Frame | Beverage Board |
| MERV Ratings Available | 8, 11, 13 |
| Lifespan | Up to 12 Months |
| Origin | Made in USA |