---
title: "C5 Window Envelopes — £26K/yr Amazon UK Niche (2026) - Flapen"
canonical_url: "https://flapen.com/research/uk/stationery-office-supplies/c5-window-envelopes"
last_updated: "2026-07-31T08:55:13.156Z"
locale: en
meta:
description: "Niche score 37/100 · £26K/yr market · 9K searches/yr · £11.70 avg price. Doesn't clear our bar today. Data updated Jul 2026."
"og:description": "Niche score 37/100 · £26K/yr market · 9K searches/yr · £11.70 avg price. Doesn't clear our bar today. Data updated Jul 2026."
"og:title": "C5 Window Envelopes — £26K/yr Amazon UK Niche (2026) - Flapen"
---
# **c5 window envelopes**
**Skip it**
Brand-locked demand (top 5 brands take 100% of clicks) — this niche doesn't clear our bar today.
Market size 6Growth 13Conversion 100Competition 14Returns 99Price range 28Avg price 48Brand share 0Review moat 84Quality gap 43
**Conversion**
**Incredible****23.5%**
search→purchase rate — share of searches ending in a sale
**Returns**
**Incredible****0.1%**
return rate — above 5% kills the launch gate
**Review moat**
**Great****326.33**
avg incumbent reviews — the moat a new listing must climb
**Avg price**
**Okay****£11.70**
avg listing price — sweet spot $15–$100
**Quality gap**
**Okay****4.5★**
avg incumbent rating — lower means beatable quality
**Price range**
**Okay****£2.60–£19.81**
cheapest to priciest tracked listing — scored on the share inside $15–$100
**Competition**
**Bad****83%**
top-5 click share — a locked-up shelf
**Growth**
**Bad****-24.1%**
90-day search growth — must beat 0% to launch
**Market size**
**Bad****£26K**
£26K/yr · 9K searches
**Brand share**
**Bad****100%**
top-5 brand share — brand-locked demand
According to Flapen's Amazon United Kingdom niche tracking, c5 window envelopes is a £26K/yr Amazon United Kingdom market (9K searches/yr). The top 5 brands hold 100% of demand. Verdict: Skip it — 37/100.
Data updated Jul 29, 2026 · scored weekly · [~~How we score niches ~~](https://flapen.com/research/methodology)
## **c5 window envelopes market data**
- **Units sold / yr**
- **3K–4K**
- avg 250–500/product
- **Revenue / yr**
- **£35K–£47K**
- units × avg price
- **Conversion rate**
- **23.5%**
- **Avg BSR**
- **#55**
- **Page quality**
- **0%**
- **Prime**
- **78%**
- **Sponsored**
- **89%**
- **Out of stock**
- **0.0%**
- **Avg brand age**
- **89 months**
- **Avg seller age**
- **191 days**
## **Competition & brand share**
The top 5 products capture 83% of clicks — a locked-up shelf that new listings rarely crack.
**Brands**
**4 **—flat
**Sellers**
**21**
**Top-5 brand share**
**100%**
Top 20: 100%
**Top-5 click share**
**83%**
Top 20: 100%
**Open market**
**0%**
- Postmaster39% - Q-Connect24% - Blake21% - Globe Packaging16% - Open — no brand owns it (0%)
## **Demand & seasonality**
Weekly Amazon search volume, last 103 weeks — -24.1% search growth over the last 90 days.
250150Spike '24Black Friday '24Spike '25Black Friday '25Holiday '25Spike '26 seasonDecMarJunAugNovMarMay
No pronounced peak months · busiest ÷ quietest = 1.5×
[**Open Trend **](https://flapen.com/research/uk/stationery-office-supplies/c5-window-envelopes/trend)
## **Top c5 window envelopes search terms**
- **c5 window envelopes**5K/yr-22.4%21.3% conv. - **a5 window envelopes self seal**3K/yr-24.2%27.6% conv. - **c5 window envelopes self seal 500**2K/yr-27.8%26.5% conv. [**All search terms **](https://flapen.com/research/uk/stationery-office-supplies/c5-window-envelopes/search-terms)
## **Top c5 window envelopes 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%£3K20%£5K30%£8K40%£10K1101001K10K Reviews — right = deep review moatMarket share (90d) ≈ est. sales
Beatable (≤4.3★) Contested Strong incumbent (>4.7★)
All 9 tracked products in this niche — three views at once, no toggling.
### **Top sellers**
by 90-day click share
[1**Postmaster C5 Window Envelopes 229 x 162 mm A5 90 GSM Self Seal White Bulk Business Pack of 500**Postmaster**£14.62**4.6★315 rev](https://www.amazon.co.uk/dp/B0BWZKDKHF) [2**Q-Connect C5 Envelopes Window Pocket Self Seal 90 gsm White (Pack of 500)**Q-Connect**£14.95**4.6★62 rev](https://www.amazon.co.uk/dp/B000NLV1IQ) [3**GP Globe Packaging 50 x C5 A5 White Window Self Seal Paper Envelopes (Size: 229x164mm) - Printer Safe & Fully Opaque - Security Mailing Envelopes for Home Office & Business Use**Globe Packaging**£5.43**4.6★1,659 rev](https://www.amazon.co.uk/dp/B0D6RSWQF3) [4**Postmaster A5 C5 Window Envelopes 229 x 162 mm 90 GSM Self Seal White 200 Pack**Postmaster**£8.02**4.6★315 rev](https://www.amazon.co.uk/dp/B0B2J7Y4YV) [5**Blake Purely Everyday 90 gsm C5 229 x 162 mm Pocket Self Seal Window Envelopes (12084) White - Pack of 500**Blake**£19.39**4.6★287 rev](https://www.amazon.co.uk/dp/B00QYUI45I)
**~~View all top sellers →~~**
### **Newest**
by launch date
[**Postmaster C5 Window Envelopes 229 x 162 mm A5 90 GSM Self Seal White Bulk Business Pack of 500**Postmaster**£14.62**315 rev3y ago](https://www.amazon.co.uk/dp/B0BWZKDKHF) [**Postmaster A5 C5 Window Envelopes 229 x 162 mm 90 GSM Self Seal White 200 Pack**Postmaster**£8.02**315 rev4y ago](https://www.amazon.co.uk/dp/B0B2J7Y4YV) [**Blake Purely Everyday C5 229 x 162 mm 100 gsm Pocket Peel & Seal Window Envelopes (23084/100 PR) White - Pack of 100**Blake**£6.89**91 rev8y ago](https://www.amazon.co.uk/dp/B078Y5T3HP) [**Q-Connect C5 Envelopes Window Pocket Self Seal 90gsm White (Pack of 500) 9000020**Q-Connect**£13.61**11 rev10y ago](https://www.amazon.co.uk/dp/B01DSRVR26) [**Blake Purely Everyday 90 gsm C5 229 x 162 mm Pocket Self Seal Window Envelopes (12084) White - Pack of 500**Blake**£19.39**287 rev12y ago](https://www.amazon.co.uk/dp/B00QYUI45I)
**~~View all new products →~~**
### **Trending**
90-day click momentum
[**Blake Purely Everyday C5 162 x 229 mm 90 gsm Self Seal Wallet High Window Envelopes (1709) White - Pack of 500**Blake**£19.81**4.2★**▲ 106%**](https://www.amazon.co.uk/dp/B00Q4R1BE2) [**Blake Purely Everyday C5 229 x 162 mm 90 gsm Self Seal Window Pocket Envelopes (13084/25 PR) White - Pack of 25**Blake**£2.60**4.5★**▲ 15%**](https://www.amazon.co.uk/dp/B00LY25COW) [**Blake Purely Everyday 90 gsm C5 229 x 162 mm Pocket Self Seal Window Envelopes (12084) White - Pack of 500**Blake**£19.39**4.6★**— 10%**](https://www.amazon.co.uk/dp/B00QYUI45I) [**Q-Connect C5 Envelopes Window Pocket Self Seal 90 gsm White (Pack of 500)**Q-Connect**£14.95**4.6★**— 7%**](https://www.amazon.co.uk/dp/B000NLV1IQ) [**Postmaster A5 C5 Window Envelopes 229 x 162 mm 90 GSM Self Seal White 200 Pack**Postmaster**£8.02**4.6★**— 0%**](https://www.amazon.co.uk/dp/B0B2J7Y4YV)
**~~View all trending →~~**
## **What buyers say about c5 window envelopes**
What buyers praise and complain about, mined from review topics.
### **What buyers love **
**Quality-Overall**33%
*“Great product - as described”*
**Advertised Vs Actual Product**33%
*“Does what was promised”*
**Value For Money**25%
*“Great value”*
**Size-Overall**8%
*“Fit for purpose”*
### **Top return reasons **
**Advertised Vs Actual Product**27%
**Moist/Dry**14%
**Quality-Overall**9%
**Ethical Trade/Fair Trade**9%
**Defective Material/Parts**9%
**Size-Overall**9%
**Paper Quality**9%
**Material Quality**9%
**Adhesion/Stickiness**5%
## **Common questions**
- **Is c5 window envelopes profitable to sell on Amazon United Kingdom?**
- The niche generates £26K/yr across 9 tracked products. 90-day search growth is -24.1%. Flapen's verdict: Skip it (37/100).
- **How competitive is the c5 window envelopes niche?**
- 4 brands and 21 sellers compete. The top 5 products take 83% of clicks and top 5 brands hold 100% of demand.
- **When does demand for c5 window envelopes peak?**
- Demand is steady year-round — the busiest month runs 1.5× the quietest.
- **What does it cost to enter the c5 window envelopes niche?**
- Listings span £2.60–£19.81; the average listing price is £11.70 (sweet spot $15–$100). The average incumbent carries 326 reviews — the moat a new listing must climb.
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