---
title: "4 Inch Air Filter — $89K/yr Amazon US Niche (2026) - Flapen"
canonical_url: "https://flapen.com/research/us/automotive/4-inch-air-filter"
last_updated: "2026-08-09T12:45:41.325Z"
locale: en
meta:
description: "Niche score 53/100 · $89K/yr market · 61K searches/yr · $32.07 avg price. A small market ($89K/yr) keeps it on the watch list. Data updated Jul 2026."
"og:description": "Niche score 53/100 · $89K/yr market · 61K searches/yr · $32.07 avg price. A small market ($89K/yr) keeps it on the watch list. Data updated Jul 2026."
"og:title": "4 Inch Air Filter — $89K/yr Amazon US Niche (2026) - Flapen"
---
# **4 inch air filter**
**Worth a look**
Shows a sweet-spot price point ($32.07 avg), but a small market ($89K/yr) keeps it on the watch list.
Market size 22Growth 22Conversion 55Competition 73Returns 75Price range 87Avg price 95Brand share 59Review moat 64Quality gap 38
**Avg price**
**Incredible****$32.07**
avg listing price — sweet spot $15–$100
**Price range**
**Great****$9.57–$65.39**
cheapest to priciest tracked listing — scored on the share inside $15–$100
**Returns**
**Great****2.0%**
return rate — above 5% kills the launch gate
**Competition**
**Good****41%**
top-5 click share — leaders hold, buyers still browse
**Review moat**
**Good****940.71**
avg incumbent reviews — the moat a new listing must climb
**Brand share**
**Good****70%**
top-5 brand share — brands hold most of the demand
**Conversion**
**Good****4.6%**
search→purchase rate — share of searches ending in a sale
**Quality gap**
**Okay****4.5★**
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 ~~](https://flapen.com/research/methodology)
## **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.
1K750Spike '25Spike '26 seasonSepDecMarJunAugNovMarMay
No pronounced peak months · busiest ÷ quietest = 1.5×
[**Open Trend **](https://flapen.com/research/us/automotive/4-inch-air-filter/trend)
## **Top 4 inch air filter search terms**
- **4 inch air filter**23K/yr+7.3%3.3% conv. - **4 air filter**12K/yr-6.1%4.1% conv. - **4in air filter**6K/yr-2.1%5.1% conv. - **4 inch cold air intake filter**5K/yr-16.0%3.6% conv. - **4 inch filter**4K/yr-4.3%2.3% conv. - **4 inch cone air filter**4K/yr-6.2%3.5% conv. - **4 filter**3K/yr-1.8%1.8% conv. - **4 air filter cone**4K/yr-62.0%3.8% conv. [**All search terms **](https://flapen.com/research/us/automotive/4-inch-air-filter/search-terms)
## **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.
0%4%$4K8%$7K12%$11K16%$14K1101001K10K Reviews — right = deep review moatMarket share (90d) ≈ est. sales
Beatable (≤4.3★) Contested Strong incumbent (>4.7★)
All 24 tracked products in this niche — three views at once, no toggling.
### **Top sellers**
by 90-day click share
[1**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**$35.24**4.6★5,136 rev](https://www.amazon.com/dp/B00AFRIVNQ) [2**RYANSTAR RACING 102mm 4 High Flow Round Tapered Cone Cool Air Filter Cleaner with Top Filter Design Short 231mm tall**RYANSTAR RACING**$20.58**4.5★783 rev](https://www.amazon.com/dp/B0CCS6MPJV) [3**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**$56.73**4.6★254 rev](https://www.amazon.com/dp/B01G463QNQ) [4**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**$65.39**4.8★589 rev](https://www.amazon.com/dp/B00029WZFC) [5**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**$27.82**4.4★85 rev](https://www.amazon.com/dp/B0FL219PFX)
**~~View all top sellers →~~**
### **Newest**
by launch date
[**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**$27.82**85 rev9mo ago](https://www.amazon.com/dp/B0FL219PFX) [**RYANSTAR RACING Red 4 102mm Inlet Cone Dry Air Filter High Flow Performance Cold Air Intake Filter Washable & Reusable Universal Replacement**RYANSTAR RACING**$17.64**620 rev10mo ago](https://www.amazon.com/dp/B0FQ4WFJ8K) [**4 Inlet Car Performance Reusable Cold Air Intake Filter Universal 100mm Clamp-on Cone Replacement Dry Air Filter (Red)**MIADILA**$18.19**23 rev10mo ago](https://www.amazon.com/dp/B0FFTLMPTV) [**4 Inlet Car Performance Reusable Cold Air Intake Filter Universal 100mm Clamp-on Cone Replacement Dry Air Filter (Black)**MIADILA**$19.00**23 rev10mo ago](https://www.amazon.com/dp/B0FFTH6YSD) [**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**$25.57**62 rev11mo ago](https://www.amazon.com/dp/B0FCFB1JPL)
**~~View all new products →~~**
### **Trending**
90-day click momentum
[**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**$27.82**4.4★**▲ 196%**](https://www.amazon.com/dp/B0FL219PFX) [**4 Inlet Car Performance Reusable Cold Air Intake Filter Universal 100mm Clamp-on Cone Replacement Dry Air Filter (Red)**MIADILA**$18.19**4.3★**▲ 94%**](https://www.amazon.com/dp/B0FFTLMPTV) [**RYANSTAR RACING Red 4 102mm Inlet Cone Dry Air Filter High Flow Performance Cold Air Intake Filter Washable & Reusable Universal Replacement**RYANSTAR RACING**$17.64**4.6★**▲ 91%**](https://www.amazon.com/dp/B0FQ4WFJ8K) [**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**$45.02**4.7★**▲ 77%**](https://www.amazon.com/dp/B09RQCX5YR) [**DVPARTS 4 Blue Cold Air Intake Filter DP0235 for All Rudys 4 Intakes**DVPARTS**$36.67**4.2★**▲ 77%**](https://www.amazon.com/dp/B0FCMKFC7Z)
**~~View all trending →~~**
## **What buyers say about 4 inch air filter**
What buyers praise and complain about, mined from review topics.
### **What buyers love **
**Quality-Overall**21%
*“Great quality product,fast shipping,and honestly way better then I expected for the cost”*
**Filtration**18%
*“Strong filter”*
**Size-Overall**17%
*“Good fit as expected”*
**Value For Money**16%
*“Good price”*
**Advertised Vs Actual Product**7%
*“Worked as advertised”*
**Assembly/Installation**3%
*“Easy to install”*
**Strength**2%
*“Sturdy”*
**Efficiency**2%
*“they work great in my HVAC”*
**Ease Of Use**2%
*“Easy”*
**Smell**2%
*“Eliminates even the dankiest odors”*
### **What buyers complain about **
**Size-Overall**42%
*“DOES NOT FIT”*
**Filtration**15%
*“Filter size too larger”*
**Quality-Overall**6%
*“Quality control is not the best. for a brand name”*
**Advertised Vs Actual Product**5%
*“False advertising”*
**Compatibility-Overall**3%
*“Does not fit Honeywell filter holder”*
**Value For Money**2%
*“for $10 less per filter”*
**Thickness**2%
*“the thickness turned out to be the problem”*
**Design-Overall**2%
*“Not very well built”*
**Spray/Flow**2%
*“Flow is low”*
**Functionality-Overall**2%
*“The last one I bought is not working at all”*
### **Top return reasons **
**Size-Overall**72%
**Filtration**10%
**Compatibility-Overall**8%
**Value For Money**4%
**Advertised Vs Actual Product**2%
**Functionality-Overall**1%
**Thickness**1%
**Defective Material/Parts**1%
**Product Condition**0%
**Width**0%
## **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.
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