4 inch air filter
Worth a lookShows a sweet-spot price point ($32.07 avg), but a small market ($89K/yr) keeps it on the watch list.
Avg price
Incredible$32.07avg listing price — sweet spot $15–$100
Price range
Great$9.57–$65.39cheapest to priciest tracked listing — scored on the share inside $15–$100
Returns
Great2.0%return rate — above 5% kills the launch gate
Competition
Good41%top-5 click share — leaders hold, buyers still browse
Review moat
Good940.71avg incumbent reviews — the moat a new listing must climb
Brand share
Good70%top-5 brand share — brands hold most of the demand
Conversion
Good4.6%search→purchase rate — share of searches ending in a sale
Quality gap
Okay4.5★avg incumbent rating — lower means beatable quality
Market size
Bad$89K$89K/yr · 61K searches
Growth
Bad-6.9%90-day search growth — must beat 0% to launch
According to Flapen's Amazon United States niche tracking, 4 inch air filter is a $89K/yr Amazon United States market (61K searches/yr). The top 5 brands hold 70% of demand. Verdict: Worth a look — 53/100.
Data updated Jul 9, 2026 · scored weekly · How we score niches
4 inch air filter market data
- Units sold / yr
- 3K–3K
- avg 0–100/product
- Revenue / yr
- $80K–$96K
- units × avg price
- Conversion rate
- 4.6%
- Avg BSR
- #1,084
- Page quality
- 0%
- Prime
- 100%
- Sponsored
- 76%
- Out of stock
- 2.1%
- Avg brand age
- 49 months
- Avg seller age
- 175 days
Competition & brand share
The top 5 products take 41% of clicks — established leaders, but buyers still shop beyond them.Brands
19 rising
Sellers
79
Top-5 brand share
70%
Top 20: 100%
Top-5 click share
41%
Top 20: 81%
Open market
26%
- K&N39%
- RYANSTAR RACING17%
- muge racing5%
- MIADILA5%
- TIEVISHO4%
- Filtrete4%
Demand & seasonality
Weekly Amazon search volume, last 104 weeks — -6.9% search growth over the last 90 days.No pronounced peak months · busiest ÷ quietest = 1.5×
Top 4 inch air filter search terms
- 4 inch air filter23K/yr
- 4 air filter12K/yr
- 4in air filter6K/yr
- 4 inch cold air intake filter5K/yr
- 4 inch filter4K/yr
- 4 inch cone air filter4K/yr
- 4 filter3K/yr
- 4 air filter cone4K/yr
Top 4 inch air filter products on Amazon
Each bubble is one product — market share against review moat; bubble size tracks estimated sales, color grades how beatable the incumbent looks.
All 24 tracked products in this niche — three views at once, no toggling.
Top sellers
by 90-day click share
K&N High-Flow Original Lifetime Universal Clamp-On Air Filter: High Performance Premium: Flange Diameter: 4 In Filter Height: 5.5 In Flange Length: 1.125 In Shape: Round Tapered RG-1001RD
K&N$35.244.6★5,136 rev
RYANSTAR RACING 102mm 4 High Flow Round Tapered Cone Cool Air Filter Cleaner with Top Filter Design Short 231mm tall
RYANSTAR RACING$20.584.5★783 rev
K&N High-Flow Original Lifetime Universal Clamp-On Air Filter: High Performance Premium Washable: Flange Diameter: 4 In Filter Height: 6 In Flange Length: 1.75 In Shape: Round Tapered RE-0850
K&N$56.734.6★254 rev
K&N High-Flow Original Lifetime Universal Clamp-On Air Filter: High Performance Premium Washable: Flange Diameter: 4 In Filter Height: 9 In Flange Length: 1.75 In Shape: Round Tapered RE-0870
K&N$65.394.8★589 rev
3 3.5 4 Inch Cold Air Intake Filter 76mm 89mm 101mm High Performance Washable 3 Sizes in 1 Clamp-On Replacement Cone Air Filter Black
TIEVISHO$27.824.4★85 rev
Newest
by launch date3 3.5 4 Inch Cold Air Intake Filter 76mm 89mm 101mm High Performance Washable 3 Sizes in 1 Clamp-On Replacement Cone Air Filter Black
TIEVISHO$27.8285 rev
RYANSTAR RACING Red 4 102mm Inlet Cone Dry Air Filter High Flow Performance Cold Air Intake Filter Washable & Reusable Universal Replacement
RYANSTAR RACING$17.64620 rev
4 Inlet Car Performance Reusable Cold Air Intake Filter Universal 100mm Clamp-on Cone Replacement Dry Air Filter (Red)
MIADILA$18.1923 rev
4 Inlet Car Performance Reusable Cold Air Intake Filter Universal 100mm Clamp-on Cone Replacement Dry Air Filter (Black)
MIADILA$19.0023 rev
3 3.5 4 Inlet Car Replacement Cold Air Intake Filter 76mm 89mm 102mm 3 Sizes in 1 High Flow Performance Cone Air Filter (Red)
MIADILA$25.5762 rev
Trending
90-day click momentum3 3.5 4 Inch Cold Air Intake Filter 76mm 89mm 101mm High Performance Washable 3 Sizes in 1 Clamp-On Replacement Cone Air Filter Black
TIEVISHO$27.824.4★
4 Inlet Car Performance Reusable Cold Air Intake Filter Universal 100mm Clamp-on Cone Replacement Dry Air Filter (Red)
MIADILA$18.194.3★
RYANSTAR RACING Red 4 102mm Inlet Cone Dry Air Filter High Flow Performance Cold Air Intake Filter Washable & Reusable Universal Replacement
RYANSTAR RACING$17.644.6★
Filtrete 20x25x4 Air Filter MERV 11 MPR 1000 Micro Allergen Defense 2-Pack Fits Honeywell & AprilAire AC Furnace HVAC Filters for Home Pleated Electrostatic (Actual Size 19.88 x 24.63 x 4.31 in)
Filtrete$45.024.7★
DVPARTS 4 Blue Cold Air Intake Filter DP0235 for All Rudys 4 Intakes
DVPARTS$36.674.2★
What buyers say about 4 inch air filter
What buyers praise and complain about, mined from review topics.What buyers love
“Great quality product,fast shipping,and honestly way better then I expected for the cost”
“Strong filter”
“Good fit as expected”
“Good price”
“Worked as advertised”
“Easy to install”
“Sturdy”
“they work great in my HVAC”
“Easy”
“Eliminates even the dankiest odors”
What buyers complain about
“DOES NOT FIT”
“Filter size too larger”
“Quality control is not the best. for a brand name”
“False advertising”
“Does not fit Honeywell filter holder”
“for $10 less per filter”
“the thickness turned out to be the problem”
“Not very well built”
“Flow is low”
“The last one I bought is not working at all”
Top return reasons
Common questions
- Is 4 inch air filter profitable to sell on Amazon United States?
- The niche generates $89K/yr across 38 tracked products. 2 of 6 products launched in the last 360 days are still selling. 90-day search growth is -6.9%. Flapen's verdict: Worth a look (53/100).
- How competitive is the 4 inch air filter niche?
- 19 brands and 79 sellers compete. The top 5 products take 41% of clicks and top 5 brands hold 70% of demand.
- What do buyers complain about in 4 inch air filter?
- Top complaints mined from reviews: Size-Overall, Filtration, Quality-Overall. The return rate is 2.0%.
- When does demand for 4 inch air filter peak?
- Demand is steady year-round — the busiest month runs 1.5× the quietest.
- What does it cost to enter the 4 inch air filter niche?
- Listings span $9.57–$65.39; the average listing price is $32.07 (sweet spot $15–$100). The average incumbent carries 941 reviews — the moat a new listing must climb.