---
title: "16 3/8 X 21 1/2 X1 Air Filter — $302K/yr Amazon US Niche (2026) - Flapen"
canonical_url: "https://flapen.com/research/us/tools-home-improvement/16-3-8-x-21-1-2-x1-air-filter"
last_updated: "2026-08-08T11:51:48.321Z"
locale: en
meta:
description: "Niche score 54/100 · $302K/yr market · 42K searches/yr. Brand-locked demand (top 5 brands take 94% of clicks) keeps it on the watch list. Data updated Jul 2026."
"og:description": "Niche score 54/100 · $302K/yr market · 42K searches/yr. Brand-locked demand (top 5 brands take 94% of clicks) keeps it on the watch list. Data updated Jul 2026."
"og:title": "16 3/8 X 21 1/2 X1 Air Filter — $302K/yr Amazon US Niche (2026) - Flapen"
---
# **16 3/8 x 21 1/2 x1 air filter**
**Worth a look**
Shows searches that convert (15.2% search→purchase), but brand-locked demand (top 5 brands take 94% of clicks) keeps it on the watch list.
Market size 51Growth 62Conversion 97Competition 25Returns 83Price range 95Avg price 94Brand share 14Review moat 45Quality gap 20
**Conversion**
**Incredible****15.2%**
search→purchase rate — share of searches ending in a sale
**Price range**
**Incredible****$32.71–$63.36**
cheapest to priciest tracked listing — scored on the share inside $15–$100
**Avg price**
**Great****$47.80**
avg listing price — sweet spot $15–$100
**Returns**
**Great****1.6%**
return rate — above 5% kills the launch gate
**Growth**
**Good****+39.8%**
90-day search growth — must beat 0% to launch
**Market size**
**Good****$302K**
$302K/yr · 42K searches
**Review moat**
**Okay****2,015.47**
avg incumbent reviews — the moat a new listing must climb
**Competition**
**Bad****70%**
top-5 click share — a locked-up shelf
**Quality gap**
**Bad****4.7★**
avg incumbent rating — lower means beatable quality
**Brand share**
**Bad****94%**
top-5 brand share — brand-locked demand
According to Flapen's Amazon United States niche tracking, 16 3/8 x 21 1/2 x1 air filter is a $302K/yr Amazon United States market (42K searches/yr). The top 5 brands hold 94% of demand. Demand peaks in Jun–Jul–Aug. Verdict: Worth a look — 54/100.
Data updated Jul 27, 2026 · scored weekly · [~~How we score niches ~~](https://flapen.com/research/methodology)
## **16 3/8 x 21 1/2 x1 air filter market data**
- **Units sold / yr**
- **6K–8K**
- avg 250–500/product
- **Revenue / yr**
- **$287K–$382K**
- units × avg price
- **Conversion rate**
- **15.2%**
- **Avg BSR**
- **#229**
- **Page quality**
- **0%**
- **Prime**
- **73%**
- **Sponsored**
- **80%**
- **Out of stock**
- **9.6%**
- **Avg brand age**
- **62 months**
- **Avg seller age**
- **194 days**
## **Competition & brand share**
The top 5 products capture 70% of clicks — a locked-up shelf that new listings rarely crack.
**Brands**
**8 **▲rising
**Sellers**
**13**
**Top-5 brand share**
**94%**
Top 20: 100%
**Top-5 click share**
**70%**
Top 20: 100%
**Open market**
**4%**
- Aerostar63% - Chenzhit12% - Glasfloss12% - Qingzhug4% - Fxnitang2% - Filtrete2% - Open — no brand owns it (2 brands, 4%)
## **Demand & seasonality**
Weekly Amazon search volume, last 101 weeks — +39.8% search growth over the last 90 days.
2K1KSpike '25Prime Day '25Spike '26Prime Day '26 seasonDecMarJunAugNovMarMay
Peak months: Jun, Jul, Aug · busiest ÷ quietest = 2.5×
[**Open Trend **](https://flapen.com/research/us/tools-home-improvement/16-3-8-x-21-1-2-x1-air-filter/trend)
## **Top 16 3/8 x 21 1/2 x1 air filter search terms**
- **16 3/8 x 21 1/2 x 1 air filter**28K/yr+44.7%13.2% conv. - **air filter 16 3/8 x 21 1/2 x 1**5K/yr+25.2%14.8% conv. - **ac filter 16 3/8 x 21 1/2 x1**4K/yr+70.4%12.1% conv. - **aerostar 16 3/8 x 21 1/2 x 1**3K/yr+3.3%13.9% conv. - **16 3/8 x 21 1/2 x1 air filter**1K/yr+67.2%10.4% conv. - **air filter 16 3/8 x 21 1/2 x1**637/yr-40.2%14.4% conv. - **16 3/8 x21 1/2 x1 air filters**22/yr+0.0%0.0% conv. [**All search terms **](https://flapen.com/research/us/tools-home-improvement/16-3-8-x-21-1-2-x1-air-filter/search-terms)
## **Top 16 3/8 x 21 1/2 x1 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%10%$30K20%$60K30%$91K40%$121K101001K10K Reviews — right = deep review moatMarket share (90d) ≈ est. sales
Beatable (≤4.3★) Contested Strong incumbent (>4.7★)
All 15 tracked products in this niche — three views at once, no toggling.
### **Top sellers**
by 90-day click share
[1**Aerostar 16.375x21.5x1 MERV 11 Air Filter 4 Count ACTUAL SIZE (16.50 x 21.50 x 0.75) HVAC Air Conditioning & Furnace Filter for Dust Pet Dander Smoke & Allergies (MPR 1200 / FPR 7) Made in USA**Aerostar**$33.33**4.7★4,106 rev](https://www.amazon.com/dp/B0813SW6FK) [2**Aerostar 16.375x21.5x1 MERV 8 Air Filter 6 Count ACTUAL SIZE (16.50 x 21.50 x 0.75) HVAC Air Conditioning & Furnace Filter Captures Dust Lint & Pollen (MPR 600 / FPR 5) Made in USA**Aerostar**$45.88**4.6★3,658 rev](https://www.amazon.com/dp/B073VGH6T7) [3**Chenzhit (6 Pack) 16 3/8x21 1/2x1 Furnace Air Filters MPR 1900 & FPR 10 MERV 13 Pleated Air Filter (Actual Size: 16 3/8x21 1/2x3/4)**Chenzhit**$58.61**4.7★647 rev](https://www.amazon.com/dp/B0DZSY2SDH) [4**Glasfloss 16-3/8x21-1/2x1 MERV 10 Air Filters 6-Pack Fits Carrier**Glasfloss**$60.30**4.8★2,728 rev](https://www.amazon.com/dp/B089KTMQ4D) [5**Aerostar 16.375x21.5x1 MERV 11 - 6 Count - Pleated HVAC Furnace & Air Conditioner Filters - Removes Dust Cold & Flu Germs Lint Mold Pet Dander Allergy-Causing Pollen Smog & Smoke**Aerostar**$48.21**4.7★4,106 rev](https://www.amazon.com/dp/B01CR9JCLE)
**~~View all top sellers →~~**
### **Newest**
by launch date
[**(6 Pack) 16 3/8x21 1/2x1 Air Filter MERV 13 MPR 1900 & FPR 10 Pleated Air Filter (Actual Size: 16 3/8x21 1/2x0.75)**Fxnitang**$56.21**54 rev3mo ago](https://www.amazon.com/dp/B0GVDQN1YM) [**Chenzhit (6 Pack) 16 3/8x21 1/2x1 Furnace Air Filters MPR 1900 & FPR 10 MERV 13 Pleated Air Filter (Actual Size: 16 3/8x21 1/2x3/4)**Chenzhit**$58.61**647 rev1y ago](https://www.amazon.com/dp/B0DZSY2SDH) [**Filtrete 16.5x21.5x1 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 16.19 x 21.19 x 0.81 in)**Filtrete**$38.62**6,265 rev2y ago](https://www.amazon.com/dp/B0CZBTYX4J) [**Qingzhug 16 3/8x21 1/2x1 MERV 13 (6-Pack) Pleated Air Filter (Actual Size: 16 3/8x21 1/2x3/4) MPR 1900 & FPR 10 Furnace Air Filters**Qingzhug**$56.26**486 rev2y ago](https://www.amazon.com/dp/B0CRRWYMQN) [**Aerostar 16.375 x 21.5 x 1 MERV 6 Air Filter 6 Count ACTUAL SIZE (16.375 x 21.50 x 0.75) HVAC Furnace Filter for Dust Lint & Pollen Control (MPR 300 / FPR 3) Fits Carrier systems Made in USA**Aerostar**$32.71**242 rev2y ago](https://www.amazon.com/dp/B0CN88PXV4)
**~~View all new products →~~**
### **Trending**
90-day click momentum
[**(6 Pack) 16 3/8x21 1/2x1 Air Filter MERV 13 MPR 1900 & FPR 10 Pleated Air Filter (Actual Size: 16 3/8x21 1/2x0.75)**Fxnitang**$56.21**4.7★**▲ 191%**](https://www.amazon.com/dp/B0GVDQN1YM) [**Aerostar 16.375x21.5x1 MERV 8 Air Filter 6 Count ACTUAL SIZE (16.50 x 21.50 x 0.75) HVAC Air Conditioning & Furnace Filter Captures Dust Lint & Pollen (MPR 600 / FPR 5) Made in USA**Aerostar**$45.88**4.6★**▲ 140%**](https://www.amazon.com/dp/B073VGH6T7) [**Glasfloss 16-3/8x21-1/2x1 MERV 10 Air Filters 6-Pack Fits Carrier**Glasfloss**$60.30**4.8★**▲ 94%**](https://www.amazon.com/dp/B089KTMQ4D) [**16 3/8 x 21 1/2 x 1 Air Filter Frame with High Air Flow Washable Reusable Media Compatible Replacement for Fan Coil Filter KFAFK0212MED 317659-402 -MERV 5 Made in USA AC HVAC Furnace Filter Holder**CoreCarbon**$63.36**4.9★**▲ 81%**](https://www.amazon.com/dp/B0CF62PDTG) [**Aerostar 16.375x21.5x1 MERV 11 - 6 Count - Pleated HVAC Furnace & Air Conditioner Filters - Removes Dust Cold & Flu Germs Lint Mold Pet Dander Allergy-Causing Pollen Smog & Smoke**Aerostar**$48.21**4.7★**▲ 33%**](https://www.amazon.com/dp/B01CR9JCLE)
**~~View all trending →~~**
## **What buyers say about 16 3/8 x 21 1/2 x1 air filter**
What buyers praise and complain about, mined from review topics.
### **What buyers love **
**Quality-Overall**29%
*“Good quality”*
**Filtration**19%
*“Good Quality Filter With Reliable Fit”*
**Size-Overall**14%
*“The dimensions were accurate”*
**Value For Money**5%
*“Perfect and Great price”*
**Advertised Vs Actual Product**4%
*“As advertised”*
**Ease Of Use**4%
*“Easy to use”*
**Compatibility-Overall**4%
*“Just what I needed for my A/C unit”*
**Durability**3%
*“Reliable and Well Made”*
**Functionality-Overall**2%
*“do a good job catching small and large particles”*
**Ease Of Cleaning**2%
*“SO MUCH EASIER JUST WASH AND CLEAN AND REUSE”*
### **What buyers complain about **
**Size-Overall**19%
*“Was given the wrong size”*
**Durability**14%
*“These filters dont last very long because they collapse into the AC plenum within a month of use”*
**Filtration**12%
*“This filter is incredibly cheap and flimsy”*
**Quality-Overall**10%
*“very cheap”*
**Defective Material/Parts**7%
*“item is not working for me ok”*
**Value For Money**7%
*“I send lots money for this and???????? item is not working for me ok”*
**Strength**5%
*“Flimsy, very cheap”*
**Assembly/Installation**5%
*“when it literally crumbles in your hand trying to install it, its garbage”*
**Design-Overall**5%
*“Definite design flaw”*
### **Top return reasons **
**Size-Overall**62%
**Filtration**22%
**Compatibility-Overall**6%
**Value For Money**2%
**Defective Material/Parts**2%
**Advertised Vs Actual Product**1%
**Quality-Overall**1%
**Certifications**1%
**Thickness**1%
**Functionality-Overall**1%
## **Common questions**
- **Is 16 3/8 x 21 1/2 x1 air filter profitable to sell on Amazon United States?**
- The niche generates $302K/yr across 15 tracked products. 0 of 1 products launched in the last 360 days are still selling. 90-day search growth is +39.8%. Flapen's verdict: Worth a look (54/100).
- **How competitive is the 16 3/8 x 21 1/2 x1 air filter niche?**
- 8 brands and 13 sellers compete. The top 5 products take 70% of clicks and top 5 brands hold 94% of demand.
- **What do buyers complain about in 16 3/8 x 21 1/2 x1 air filter?**
- Top complaints mined from reviews: Size-Overall, Durability, Filtration. The return rate is 1.6%.
- **When does demand for 16 3/8 x 21 1/2 x1 air filter peak?**
- Demand peaks in Jun–Jul–Aug; the busiest month runs 2.5× the quietest.
- **What does it cost to enter the 16 3/8 x 21 1/2 x1 air filter niche?**
- Listings span $32.71–$63.36; the average listing price is $47.80 (sweet spot $15–$100). The average incumbent carries 2,015 reviews — the moat a new listing must climb.
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