GermGuardian Air Purifier Replacement Filters
October 8, 2026
TL;DR
Most GermGuardian air purifiers take one of three filters: Filter B (FLT4825), Filter C (FLT5000) or Filter E (FLT4100). Look up your model number in the finder below, and you’ll know which Filterbuy size to order: 4x16, 4x19 or 4x8. Filterbuy makes all three in its U.S. plants as True HEPA and activated-carbon assemblies, ships them free, and rates each one for about 90 days of use.
Key Takeaways
The FLT4825 is GermGuardian Filter B. Filterbuy’s 4x16 replacement fits the same AC4825, AC4820, AC4870, AC4900, AC4300 and CDAP4500 series.
The FLT5000 is GermGuardian Filter C. Filterbuy’s 4x19 replacement fits the AC5000, AC5250PT, AC5300 and AC5350 towers.
Filterbuy’s replacements are rated True HEPA. The rating means 99.97% capture at 0.3 microns, which the U.S. EPA identifies as the hardest particle size to trap.
Plan on a new assembly about every 90 days.
Check your warranty before you switch. GermGuardian recommends genuine parts, but the FTC has warned air purifier sellers that tying a warranty to branded parts generally breaks federal law.
Which Filter Does My GermGuardian Air Purifier Use?
Every GermGuardian filter has a letter and an FLT part number. Most owners need one of three: Filter B (FLT4825) for mid-size towers, Filter C (FLT5000) for large towers, or Filter E (FLT4100) for tabletop units. Retailer listings don’t always agree on which models each filter fits, so Filterbuy built this finder from the model lists on its product pages.
| GermGuardian Filter | Fits These Purifier Models | Filterbuy Replacement | Matching Carbon Pre-Filter |
|---|---|---|---|
| Filter B (FLT4825) | GermGuardian AC4300BPTCA, AC4300WPT, AC4820, AC4825, AC4825E, AC4825W, AC4850PT, AC4870, AC4880, AC4900, AC4900CA, CDAP4500BCA, CDAP4500WCA; PureGuardian AP2200CA; Black+Decker BXAP148 | 4×16 GermGuardian Replacement | Filter B Carbon Pre-Filter (4-Pack) |
| Filter C (FLT5000 or FLT5250PT) | GermGuardian AC5000E, AC5000CA, AC5250PT, AC5300B, AC5300BCA, AC5350B, AC5350BCA, AC5350W, CDAP5500BCA, CDAP5500WSP; PureGuardian AP2800CA; Black+Decker BXAP250; Idylis IAP-GG-125 | 4×19 GermGuardian Replacement | Filter C Carbon Pre-Filter (4-Pack) |
| Filter E (FLT4100) | GermGuardian AC4100, AC4100CA, AC4150B, AC4150BLCA, AC4150P, AC4150PCA, AC4175, AC4175W | 4×8 GermGuardian Replacement | Filter E Carbon Pre-Filter (4-Pack) |
Filters B and C look alike, but they aren’t interchangeable. Filter C is taller, which is why Filterbuy names its replacements by size: 4x16 for Filter B and 4x19 for Filter C. Filterbuy’s GermGuardian line covers Filters B, C and E; if your model isn’t listed, use the filter named in its manual.
How Do I Find My GermGuardian Model Number?
You’ll find the model number on a rating label on the purifier’s housing or filter door. It starts with letters like AC, CDAP or AP, followed by four digits.
For AC models, the first two digits give you a shortcut. AC43xx, AC48xx and AC49xx units take Filter B; AC50xx, AC52xx and AC53xx units take Filter C; and AC41xx units take Filter E.
Label worn off? Measure the old filter’s height instead.
About 8.25 in.: Filter E (FLT4100)
About 15.75 in.: Filter B (FLT4825)
About 19.25 in.: Filter C (FLT5000)
Filterbuy GermGuardian Replacement Filter Specifications
All three replacements are built the same way: a pleated True HEPA panel paired with an activated-carbon panel.
| Specification | 4×16 (Filter B) | 4×19 (Filter C) | 4×8 (Filter E) |
|---|---|---|---|
| Replaces | GermGuardian FLT4825 | GermGuardian FLT5000 | GermGuardian FLT4100 |
| Filter size | 4×16" | 4×19" | 4×8" |
| Filtration rating | True HEPA, 99.97% at 0.3 microns | True HEPA, 99.97% at 0.3 microns | True HEPA, 99.97% at 0.3 microns |
| Replace every | ~90 days | ~90 days | ~90 days |
| Compatible brands | GermGuardian, PureGuardian, Black+Decker | GermGuardian, PureGuardian, Black+Decker, Idylis | GermGuardian |
| Country of origin | Made in the USA | Made in the USA | Made in the USA |
| Model/SKU | PUR-GGR-HEPA | PUR-GGC-HEPA | PUR-GGE-HEPA |
| Price, 1 filter | $14.99 | $24.99 | $14.99 |
| Price each, 4+ filters | $10.49 Save 30% | $17.49 Save 30% | $10.49 Save 30% |
| Auto-delivery price | $14.24 Save 5% | $23.74 Save 5% | $14.24 Save 5% |
| Shop | Shop 4×16 | Shop 4×19 | Shop 4×8 |
How Often Should You Replace a GermGuardian Filter?
Filterbuy recommends a new assembly about every 90 days, and the carbon is the reason. The carbon pre-filter fills with odors well before the HEPA panel behind it clogs. GermGuardian rates its genuine combination filters for 6–8 months but suggests changing the carbon every 2–3 months, so a full swap at 90 days keeps both layers working. For details, see how often each air purifier filter layer needs replacing.
Replace it sooner if you notice these signs it’s time to replace your air purifier filter:
The filter-change light comes on.
The pleats look gray or brown instead of white.
Cooking or pet odors linger longer than they used to.
Airflow from the top vent feels weaker at the same fan speed.
“The pre-filter is the part people skip, and it is the one I find caked when someone tells me their purifier stopped moving air. A HEPA filter rated for a year gets thrown out at eight months because nothing was catching the dust in front of it.”
David Clark | Licensed HVAC Technician, Filterbuy HVAC Solutions
Keeping a genuine filter? You can still refresh the carbon on GermGuardian’s 2–3 month schedule. Filterbuy’s pre-cut carbon pre-filters come four to a pack for $16.85, or roughly $4.21 per change.
How to Replace a GermGuardian Air Purifier Filter
Power off and unplug the unit.
Open the filter access panel. On GermGuardian towers, the rear grille doubles as the filter cover and air intake. Pull out the old filter and note which way it faces.
Slide in the new filter. Point the dark carbon side toward the intake grille (see which way an air purifier filter goes). Filterbuy replacements arrive as one assembly with the carbon pre-filter attached.
Restart the purifier. Close the panel, plug it in and reset the indicator. On AC4825 and AC5000-series towers, hold the UV button for five seconds. Filter light won’t clear?
Compatible vs. Genuine GermGuardian Filters: What’s the Difference?
Genuine filters are made by Guardian Technologies, while compatible filters come from other manufacturers and are built to fit the same units. Both are rated True HEPA, so price and schedule are where they differ.
Genuine GermGuardian vs. Filterbuy Compatible Filters
| Detail | Genuine GermGuardian (FLT4825 / FLT5000 / FLT4100) |
Filterbuy Compatible (4×16 / 4×19 / 4×8) |
|---|---|---|
| Made by | Guardian Technologies | Filterbuy, made in the USA |
| Filtration rating | True HEPA, per GermGuardian listings | True HEPA, 99.97% at 0.3 microns |
| Carbon layer | Included in the combination filter | Attached; ships as a complete assembly |
| Replacement interval | 6–8 months (carbon layer every 2–3 months) | About every 90 days (full assembly) |
| Price, single filter | $29.99 for the FLT5000 on GermGuardian’s official store | $24.99 for the 4×19 (Filter C); $14.99 for the 4×16 and 4×8 |
| Multi-pack pricing | Varies by retailer | 30% off each in packs of 4 or more |
| Shipping | Varies by retailer | Free; ships in 24 business hours |
| Returns and fit | Retailer return policy | Hassle-free returns and free exchanges |
| Warranty note | GermGuardian advises genuine parts to maintain performance | Federal law generally bars voiding a warranty over third-party parts |
Filterbuy prices from Filterbuy product pages; genuine price from GermGuardian’s FLT5000 listing on lasko.com, both checked October 8, 2026.
Our take: Compare the cost per change, not the price per box. In a four-pack, a 4x19 costs $17.49, about 42% less than a genuine FLT5000 at $29.99. Every change also brings fresh carbon, in line with GermGuardian’s 2–3 month advice.
Supporting Statistics: Research on the Air in Your Home
Three U.S. findings shape how Filterbuy builds and schedules its filters.
About 90% of our time is spent indoors.
Why it matters: Most of your air exposure happens at home.
Pet allergens are in nearly every U.S. home.
Dog allergen: 100% of homes. Cat allergen: 99.9%.
Only 49.1% had a pet in the prior six months.
Why it matters: True HEPA helps, even without pets. See pet dander tips.
76 million Americans live with failing year-round particle pollution.
Why it matters: Fine particles drift indoors. Above AQI 100, pair a MERV 13 HVAC filter with a HEPA purifier in each room.
Why Order GermGuardian Replacement Filters From Filterbuy?
We’ve been making air filters in our own U.S. plants since 2013, with factories in Alabama, Florida, Pennsylvania and Utah. Buy a four-pack to save 30% per filter, or set up auto-delivery so the next one arrives on schedule.
Choose the replacement that fits your purifier
GermGuardian Filter FAQs
Is The Flt4825 The Same As Filter B?
Yes. FLT4825 is GermGuardian’s part number for Filter B, the combination True HEPA and carbon filter in the AC4825, AC4900 and AC4300 series. Filterbuy’s 4x16 GermGuardian replacement is the compatible version.
Is The Flt5000 The Same As Filter C?
Yes. FLT5000 is the part number for Filter C, which fits the AC5000, AC5250PT and AC5350 towers. The FLT5250PT is a pet version of the same filter, and Filterbuy’s 4x19 replacement fits purifiers that use either one.
Can I Wash And Reuse A Germguardian Hepa Filter?
No. Water damages the fine fibers in True HEPA media, so the filter can’t be washed and reused. The EPA’s Guide to Air Cleaners in the Home notes that every filter needs regular replacement, since a dirty, overloaded filter won’t work well.
What Should I Do When The AQI Climbs Over 100?
Run a True HEPA purifier in each room you use to capture fine airborne particles such as dust, pollen, pet dander, mold spores and smoke. If your home has central HVAC, also switch to a MERV 13 filter, the rating the EPA recommends when your system can handle it, and set the fan to On. See what an AQI above 100 means.
Glossary
Filterbuy: A U.S. air filter manufacturer that makes compatible GermGuardian replacements.
GermGuardian: A brand of portable air purifiers made by Guardian Technologies.
Filter B / FLT4825: GermGuardian’s combination True HEPA and carbon filter for AC4825, AC4900, AC4300 and CDAP4500 purifiers.
Filter C / FLT5000: GermGuardian’s larger combination True HEPA and carbon filter for AC5000, AC5250PT, AC5300 and AC5350 purifiers.
Filter E / FLT4100: GermGuardian’s combination filter for AC4100, AC4150 and AC4175 tabletop purifiers.
HEPA (High-Efficiency Particulate Air): A pleated mechanical filter that, per the U.S. Department of Energy definition cited by the EPA, removes at least 99.97% of particles 0.3 microns in size.
True HEPA: A filter that meets the full HEPA standard, as opposed to “HEPA-type” filters that do not.
Activated carbon pre-filter: A charcoal layer in front of the HEPA filter that traps large dust and hair and adsorbs odors and gases; see carbon vs. HEPA.
AQI (Air Quality Index): The EPA’s 0 to 500 outdoor air scale; readings above 100 are unhealthy for sensitive groups.
MERV 13: An HVAC filter rating; the EPA recommends at least MERV 13 when a system can handle it.
Micron: One-millionth of a meter, used to measure particle size.
Compatible filter: A replacement built by another maker to fit an original brand’s equipment.
About the Author and Reviewer
Michelle Wan is Brand Manager and Air Quality Writer at Filterbuy (B.A., University of California, Santa Cruz). Because she works directly with Filterbuy’s U.S. manufacturing teams, she writes from how filters are built and used. David Clark, Licensed HVAC Technician at Filterbuy HVAC Solutions, reviewed this page for technical accuracy.
Filterbuy is not affiliated with or endorsed by GermGuardian, Guardian Technologies, PureGuardian, Black+Decker or Idylis. Brand and model names are used only to show compatibility.
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