---
title: "17.5x21x1 Air Filter — $31K/yr Amazon US Niche (2026) - Flapen"
canonical_url: "https://flapen.com/research/us/tools-home-improvement/17-5x21x1-air-filter"
last_updated: "2026-08-08T11:07:25.597Z"
locale: en
meta:
description: "Niche score 42/100 · $31K/yr market · 8K searches/yr · $49.40 avg price. Doesn't clear our bar today. Data updated Jul 2026."
"og:description": "Niche score 42/100 · $31K/yr market · 8K searches/yr · $49.40 avg price. Doesn't clear our bar today. Data updated Jul 2026."
"og:title": "17.5x21x1 Air Filter — $31K/yr Amazon US Niche (2026) - Flapen"
---
# **17.5x21x1 air filter**
**Skip it**
Brand-locked demand (top 5 brands take 97% of clicks) — this niche doesn't clear our bar today.
Market size 8Growth 53Conversion 77Competition 8Returns 96Price range 95Avg price 93Brand share 6Review moat 41Quality gap 21
**Returns**
**Incredible****0.7%**
return rate — above 5% kills the launch gate
**Price range**
**Incredible****$38.40–$75.13**
cheapest to priciest tracked listing — scored on the share inside $15–$100
**Avg price**
**Great****$49.40**
avg listing price — sweet spot $15–$100
**Conversion**
**Great****7.5%**
search→purchase rate — share of searches ending in a sale
**Growth**
**Good****+24.4%**
90-day search growth — must beat 0% to launch
**Review moat**
**Okay****2,358.88**
avg incumbent reviews — the moat a new listing must climb
**Quality gap**
**Bad****4.7★**
avg incumbent rating — lower means beatable quality
**Market size**
**Bad****$31K**
$31K/yr · 8K searches
**Competition**
**Bad****91%**
top-5 click share — a locked-up shelf
**Brand share**
**Bad****97%**
top-5 brand share — brand-locked demand
According to Flapen's Amazon United States niche tracking, 17.5x21x1 air filter is a $31K/yr Amazon United States market (8K searches/yr). The top 5 brands hold 97% of demand. Verdict: Skip it — 42/100.
Data updated Jul 27, 2026 · scored weekly · [~~How we score niches ~~](https://flapen.com/research/methodology)
## **17.5x21x1 air filter market data**
- **Units sold / yr**
- **750–1K**
- avg 100–250/product
- **Revenue / yr**
- **$37K–$49K**
- units × avg price
- **Conversion rate**
- **7.5%**
- **Avg BSR**
- **#581**
- **Page quality**
- **0%**
- **Prime**
- **38%**
- **Sponsored**
- **38%**
- **Out of stock**
- **3.4%**
- **Avg brand age**
- **73 months**
- **Avg seller age**
- **229 days**
## **Competition & brand share**
The top 5 products capture 91% of clicks — a locked-up shelf that new listings rarely crack.
**Brands**
**6 **—flat
**Sellers**
**14**
**Top-5 brand share**
**97%**
Top 20: 100%
**Top-5 click share**
**91%**
Top 20: 100%
**Open market**
**0%**
- Filter King51% - SpiroPure22% - Filtrete10% - WholesaleHVACDirect10% - QCYZTL4% - Glasfloss3% - Open — no brand owns it (0%)
## **Top 17.5x21x1 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%15%$5K30%$9K45%$14K60%$18K1101001K10K Reviews — right = deep review moatMarket share (90d) ≈ est. sales
Beatable (≤4.3★) Contested Strong incumbent (>4.7★)1 product missing review or click data not plotted
All 8 tracked products in this niche — three views at once, no toggling.
### **Top sellers**
by 90-day click share
[1**Filter King 17.5x21x1 Air Filter (MERV 8) (4-Pack) Dust & Allergy Control AC Furnace Filters MADE IN USA HVAC Pleated Electrostatic (Actual Size: 17.5 x 21 x .75)**Filter King**$51.25**4.7★4,436 rev](https://www.amazon.com/dp/B0CMS5NX9K) [2**SpiroPure 17.5X21X1 MERV 8 Geothermal Air Filters - Made in USA (6 Pack)**SpiroPure**$52.77**4.7★325 rev](https://www.amazon.com/dp/B07R4J9645) [3**WholesaleHVACDirect 17.5x21x1 Air Filter (MERV 8) (4-Pack) King Dust & Allergy Control AC Furnace Filters MADE IN USA HVAC Pleated Electrostatic (Actual Size: 17.5 x 21 x .75)**WholesaleHVACDirect**$38.40**0.0★0 rev](https://www.amazon.com/dp/B0H1QTY78V) [4**Filtrete 17x21x1 AC Furnace Air Filter MERV 8 MPR 700 Tough on Pollen Easy on Airflow 3-Month Pleated 1-Inch Electrostatic Air Cleaning Filter 4-Pack (Actual Size 16.69 x 20.69 x 0.81 in)**Filtrete**$42.30**4.7★6,265 rev](https://www.amazon.com/dp/B0CZC54GBV) [5**Filter King 17x21x1 Air Filter (MERV 8) (4-Pack) Dust & Allergy Control AC Furnace Filters MADE IN USA HVAC Pleated Electrostatic (Actual Size: 17 x 21 x .75)**Filter King**$38.63**4.7★1,569 rev](https://www.amazon.com/dp/B07FR2HT4B)
**~~View all top sellers →~~**
### **Newest**
by launch date
[**WholesaleHVACDirect 17.5x21x1 Air Filter (MERV 8) (4-Pack) King Dust & Allergy Control AC Furnace Filters MADE IN USA HVAC Pleated Electrostatic (Actual Size: 17.5 x 21 x .75)**WholesaleHVACDirect**$38.40**0 rev2mo ago](https://www.amazon.com/dp/B0H1QTY78V) [**Upgraded 17.5x21x1 MERV 13 furnace replacement filter household air conditioning and air conditioning HVAC filter replacement 6 pack**QCYZTL**$75.13**5 rev10mo ago](https://www.amazon.com/dp/B0FN3FB13D) [**Glasfloss ZL 17.5x21x1 MERV 10 Pleated Air Filters. 5-Pack**Glasfloss**$53.40**6 rev1y ago](https://www.amazon.com/dp/B0F9FXXDK8) [**Filtrete 17x21x1 AC Furnace Air Filter MERV 8 MPR 700 Tough on Pollen Easy on Airflow 3-Month Pleated 1-Inch Electrostatic Air Cleaning Filter 4-Pack (Actual Size 16.69 x 20.69 x 0.81 in)**Filtrete**$42.30**6,265 rev2y ago](https://www.amazon.com/dp/B0CZC54GBV) [**Filtrete 17.5x22x1 AC Furnace Air Filter MERV 8 MPR 700 Tough on Pollen Easy on Airflow 3-Month Pleated 1-Inch Electrostatic Air Cleaning Filter 4-Pack (Actual Size 17.19 x 21.69 x 0.81 in)**Filtrete**$43.34**6,265 rev2y ago](https://www.amazon.com/dp/B0CZBYMNNZ)
**~~View all new products →~~**
### **Trending**
90-day click momentum
[**WholesaleHVACDirect 17.5x21x1 Air Filter (MERV 8) (4-Pack) King Dust & Allergy Control AC Furnace Filters MADE IN USA HVAC Pleated Electrostatic (Actual Size: 17.5 x 21 x .75)**WholesaleHVACDirect**$38.40**0.0★**▲ 266%**](https://www.amazon.com/dp/B0H1QTY78V) [**Filter King 17x21x1 Air Filter (MERV 8) (4-Pack) Dust & Allergy Control AC Furnace Filters MADE IN USA HVAC Pleated Electrostatic (Actual Size: 17 x 21 x .75)**Filter King**$38.63**4.7★**▲ 74%**](https://www.amazon.com/dp/B07FR2HT4B) [**Filter King 17.5x21x1 Air Filter (MERV 8) (4-Pack) Dust & Allergy Control AC Furnace Filters MADE IN USA HVAC Pleated Electrostatic (Actual Size: 17.5 x 21 x .75)**Filter King**$51.25**4.7★**— 7%**](https://www.amazon.com/dp/B0CMS5NX9K) [**Upgraded 17.5x21x1 MERV 13 furnace replacement filter household air conditioning and air conditioning HVAC filter replacement 6 pack**QCYZTL**$75.13**4.4★**— 10%**](https://www.amazon.com/dp/B0FN3FB13D) [**SpiroPure 17.5X21X1 MERV 8 Geothermal Air Filters - Made in USA (6 Pack)**SpiroPure**$52.77**4.7★**▼ 13%**](https://www.amazon.com/dp/B07R4J9645)
**~~View all trending →~~**
## **What buyers say about 17.5x21x1 air filter**
What buyers praise and complain about, mined from review topics.
### **What buyers love **
**Size-Overall**38%
*“Fit well”*
**Quality-Overall**25%
*“Product Quality”*
**Compatibility-Overall**13%
*“Solid product and fit perfectly in my A/C”*
**Efficiency**13%
*“Works very good”*
**Filtration**13%
*“Always have a great experience with Filter King”*
### **What buyers complain about **
**Filtration**100%
*“If it's not doing it's job, it's you, not the filter”*
### **Top return reasons **
**Size-Overall**87%
**Compatibility-Overall**7%
**Filtration**3%
**Functionality-Overall**2%
**Advertised Vs Actual Product**2%
**Defective Material/Parts**1%
**Thickness**0%
## **Common questions**
- **Is 17.5x21x1 air filter profitable to sell on Amazon United States?**
- The niche generates $31K/yr across 8 tracked products. 0 of 2 products launched in the last 360 days are still selling. 90-day search growth is +24.4%. Flapen's verdict: Skip it (42/100).
- **How competitive is the 17.5x21x1 air filter niche?**
- 6 brands and 14 sellers compete. The top 5 products take 91% of clicks and top 5 brands hold 97% of demand.
- **What do buyers complain about in 17.5x21x1 air filter?**
- Top complaints mined from reviews: Filtration. The return rate is 0.7%.
- **What does it cost to enter the 17.5x21x1 air filter niche?**
- Listings span $38.40–$75.13; the average listing price is $49.40 (sweet spot $15–$100). The average incumbent carries 2,359 reviews — the moat a new listing must climb.
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