---
title: "Pool Liner 21 Ft Round Above Ground — $125K/yr Amazon US Niche (2026) - Flapen"
canonical_url: "https://flapen.com/research/us/patio-lawn-garden/pool-liner-21-ft-round-above-ground"
last_updated: "2026-08-05T18:59:55.049Z"
locale: en
meta:
description: "Niche score 53/100 · $125K/yr market · 17K searches/yr. Brand-locked demand (top 5 brands take 98% of clicks) keeps it on the watch list. Data updated Jul 2026."
"og:description": "Niche score 53/100 · $125K/yr market · 17K searches/yr. Brand-locked demand (top 5 brands take 98% of clicks) keeps it on the watch list. Data updated Jul 2026."
"og:title": "Pool Liner 21 Ft Round Above Ground — $125K/yr Amazon US Niche (2026) - Flapen"
---
# **pool liner 21 ft round above ground**
**Worth a look**
Shows low returns (1.1%), but brand-locked demand (top 5 brands take 98% of clicks) keeps it on the watch list.
Market size 29Growth 87Conversion 37Competition 61Returns 92Price range 15Avg price 38Brand share 5Review moat 77Quality gap 68
**Returns**
**Great****1.1%**
return rate — above 5% kills the launch gate
**Growth**
**Great****+90.8%**
90-day search growth — must beat 0% to launch
**Review moat**
**Great****468.77**
avg incumbent reviews — the moat a new listing must climb
**Quality gap**
**Good****4.3★**
avg incumbent rating — lower means beatable quality
**Competition**
**Good****49%**
top-5 click share — leaders hold, buyers still browse
**Avg price**
**Okay****$256.20**
avg listing price — sweet spot $15–$100
**Conversion**
**Okay****2.9%**
search→purchase rate — share of searches ending in a sale
**Market size**
**Okay****$125K**
$125K/yr · 17K searches
**Price range**
**Bad****$48.38–$393.61**
cheapest to priciest tracked listing — scored on the share inside $15–$100
**Brand share**
**Bad****98%**
top-5 brand share — brand-locked demand
**Signals**[** High Price**](https://flapen.com/research/niches?market=us&signal=high_price "Avg price > $50")
According to Flapen's Amazon United States niche tracking, pool liner 21 ft round above ground is a $125K/yr Amazon United States market (17K searches/yr). The top 5 brands hold 98% of demand. Verdict: Worth a look — 53/100.
Data updated Jul 24, 2026 · scored weekly · [~~How we score niches ~~](https://flapen.com/research/methodology)
## **pool liner 21 ft round above ground market data**
- **Units sold / yr**
- **100–250**
- avg 0–100/product
- **Revenue / yr**
- **$26K–$64K**
- units × avg price
- **Conversion rate**
- **2.9%**
- **Avg BSR**
- **#89**
- **Page quality**
- **0%**
- **Prime**
- **27%**
- **Sponsored**
- **93%**
- **Out of stock**
- **8.1%**
- **Avg brand age**
- **36 months**
- **Avg seller age**
- **197 days**
## **Competition & brand share**
The top 5 products take 49% of clicks — established leaders, but buyers still shop beyond them.
**Brands**
**8 **▼falling
**Sellers**
**21**
**Top-5 brand share**
**98%**
Top 20: 100%
**Top-5 click share**
**49%**
Top 20: 90%
**Open market**
**1%**
- Smartline44% - Swimline25% - Blue Wave21% - VEVOR7% - Shop Square1% - TIXANF1% - Open — no brand owns it (2 brands, 1%)
## **Demand**
Weekly Amazon search volume, last 8 weeks — +90.8% search growth over the last 90 days.
1K600Spike '26May '26Jun '26Jun '26Jun '26Jun '26Jul '26Jul '26Jul '26
[**Open Trend **](https://flapen.com/research/us/patio-lawn-garden/pool-liner-21-ft-round-above-ground/trend)
## **Top pool liner 21 ft round above ground search terms**
- **21 round pool liner**5K/yr+128.0%1.4% conv. - **21 ft round pool liner**4K/yr+102.7%1.7% conv. - **21 foot pool liner**3K/yr+141.5%1.6% conv. - **pool liner 21 ft round above ground**4K/yr+24.2%1.9% conv. [**All search terms **](https://flapen.com/research/us/patio-lawn-garden/pool-liner-21-ft-round-above-ground/search-terms)
## **Top pool liner 21 ft round above ground 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%$5K8%$10K12%$15K16%$20K1101001K10K 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**Swimline 21 Foot Round Durable 20 Gauge Vinyl Wall Overlap Pool Cover Liner for 48 and 52 Inch Above Ground Swimming Pools Blue**Swimline**$201.43**4.4★972 rev](https://www.amazon.com/dp/B003TQMB86) [2**Blue Wave Emerald Coast 21 ft Round Pool Liner for Above Ground Pools**Blue Wave**$266.66**4.0★99 rev](https://www.amazon.com/dp/B09WYJNQ65) [3**Smartline 21 ft Round Swimming Pool Liner | Boulder Swirl | Overlap Style | 48-52 Inch Wall Height | 25 Gauge Vinyl | for Steel Sided Above Ground Pools | Gasket Kit Included**Smartline**$308.36**4.5★777 rev](https://www.amazon.com/dp/B00U2O5M34) [4**Blue Wave Evening Bay 21-ft Round Overlap Pool Liner for Above-Ground Steel Wall Pools Weather-Resistant Standard-Gauge Vinyl with Welded Seams for 48/54-In Depth Walls - Dark Blue**Blue Wave**$302.15**4.0★194 rev](https://www.amazon.com/dp/B09WYHWK6C) [5**Swimline LI214820 21 Foot Solid Blue Round Above Ground Swimming Pool Overlap Liner 20 Gauge Vinyl Liner for 48 to 52 Foot Pool Walls**Swimline**$167.35**4.3★1,069 rev](https://www.amazon.com/dp/B003TQMAXW)
**~~View all top sellers →~~**
### **Newest**
by launch date
[**Smartline 21 ft Round Swimming Pool Liner | Sunlight | Overlap Style | 48-52 Inch Wall Height | 20 Gauge Heavy Duty Virgin Vinyl | Designed for Steel Sided Above Ground Swimming Pools**Smartline**$262.66**256 rev5mo ago](https://www.amazon.com/dp/B0GPXWJK45) [**Smartline 21 ft Round Swimming Pool Liner | Coastal Rock | Unibead Style | 52 Inch Wall Height | 25 Gauge Heavy Duty Virgin Vinyl | Designed for Steel Sided Above Ground Pools**Smartline**$349.45**120 rev9mo ago](https://www.amazon.com/dp/B0FVMSVWZQ) [**Smartline 21 ft Round Swimming Pool Liner | Pebble Bottom | Overlap Style | 54 Inch Wall Height | 25 Gauge Heavy Duty Virgin Vinyl | Designed for Steel Sided Above Ground Pools**Smartline**$219.98**435 rev9mo ago](https://www.amazon.com/dp/B0FV3NHVNK) [**Swimline Unibead Pool Liner for Above Ground Pools StoneHarbor 21 (Round) 52 Inch Wall 25 Gauge**Swimline**$369.65**28 rev1y ago](https://www.amazon.com/dp/B0FBP495VR) [**Swimline Overlap Pool Liner for Above Ground Pools Bedrock 21 (Round) 48/52 Inch Wall 25 Gauge**Swimline**$298.75**44 rev1y ago](https://www.amazon.com/dp/B0FBHSG54Q)
**~~View all new products →~~**
### **Trending**
90-day click momentum
[**Smartline 21 ft Round Swimming Pool Liner | Coastal Rock | Overlap Style | 54 Inch Wall Height | 25 Gauge Heavy Duty Virgin Vinyl | Designed for Steel Sided Above Ground Pools**Smartline**$280.40**4.1★**▲ 63%**](https://www.amazon.com/dp/B09K4LPLZP) [**Smartline 21 ft Round Swimming Pool Liner | Sunlight | Overlap Style | 48-52 Inch Wall Height | 20 Gauge Heavy Duty Virgin Vinyl | Designed for Steel Sided Above Ground Swimming Pools**Smartline**$262.66**4.5★**▲ 62%**](https://www.amazon.com/dp/B0GPXWJK45) [**Swimline Unibead Pool Liner for Above Ground Pools StoneHarbor 21 (Round) 52 Inch Wall 25 Gauge**Swimline**$369.65**4.4★**▲ 62%**](https://www.amazon.com/dp/B0FBP495VR) [**Smartline 21 ft Round Swimming Pool Liner | Swirl Bottom | Overlap Style | 48-52 Inch Wall Height | 20 Gauge Heavy Duty Virgin Vinyl | Designed for Steel Sided Above Ground Swimming Pools**Smartline**$213.86**4.5★**▲ 56%**](https://www.amazon.com/dp/B0F1S9R8ZD) [**Blue Wave Emerald Coast 21 ft Round Pool Liner for Above Ground Pools**Blue Wave**$266.66**4.0★**▲ 52%**](https://www.amazon.com/dp/B09WYJNQ65)
**~~View all trending →~~**
## **What buyers say about pool liner 21 ft round above ground**
What buyers praise and complain about, mined from review topics.
### **What buyers love **
**Size-Overall**15%
*“Fit well”*
**Assembly/Installation**14%
*“Easy to install”*
**Quality-Overall**12%
*“Good quality”*
**Material Quality**11%
*“The material feels durable and does a great job of protecting the liner from rocks, roots, or uneven ground”*
**Thickness**9%
*“Its better than the grass being thick all around it”*
**Weight Heavy**9%
*“It very heavy duty weighted almost as much as new liner”*
**Design-Overall**3%
*“Its beautiful and very classy”*
**Strength**3%
*“Its sturdy and great quality”*
**Ease Of Use**2%
*“It was easy to lay out”*
**Drop/Impact Protection**2%
*“Great protection for your pool”*
### **What buyers complain about **
**Assembly/Installation**23%
*“Wish I had seen the issue before installing”*
**Stitch/Finish/Polish**18%
*“The seams didnt match up so the liner has creases”*
**Size-Overall**14%
*“it barely fits”*
**Durability**9%
*“Have only had it for a week, very disappointed”*
**Thickness**5%
*“Was thicker than the old one”*
**Design-Overall**5%
*“HOWEVER the Universal Bead is a tough design”*
**Material Quality**5%
*“Could be a little stronger material”*
**Plant Growth**5%
*“Weeds grow through it be weary of purchasing this”*
### **Top return reasons **
**Size-Overall**53%
**Advertised Vs Actual Product**7%
**Thin**6%
**Stitch/Finish/Polish**5%
**Quality-Overall**4%
**Thickness**3%
**Material Quality**3%
**Shape/Style**3%
**Assembly/Installation**2%
**Maintenance And Repair**2%
## **Common questions**
- **Is pool liner 21 ft round above ground profitable to sell on Amazon United States?**
- The niche generates $125K/yr across 30 tracked products. 2 of 4 products launched in the last 360 days are still selling. 90-day search growth is +90.8%. Flapen's verdict: Worth a look (53/100).
- **How competitive is the pool liner 21 ft round above ground niche?**
- 8 brands and 21 sellers compete. The top 5 products take 49% of clicks and top 5 brands hold 98% of demand.
- **What do buyers complain about in pool liner 21 ft round above ground?**
- Top complaints mined from reviews: Assembly/Installation, Stitch/Finish/Polish, Size-Overall. The return rate is 1.1%.
- **What does it cost to enter the pool liner 21 ft round above ground niche?**
- Listings span $48.38–$393.61; the average listing price is $256.20 (sweet spot $15–$100). The average incumbent carries 469 reviews — the moat a new listing must climb.
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