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Shoebox Packed In A Large Grey Mailing Bag 16" x 21" Large Grey Mailing Bags (A2 Size) – Heavy Duty Shipping for Large Items & Bundles £3.50 – £40.50Price range: £3.50 through £40.50

9″ x 12″ Grey Mailing Bags Large Letter Size (A4) – Professional Shipping for T-Shirts, Books & Documents

Price range: £2.50 through £15.36

What Fits in This Bag?

  • Single T-shirts, leggings, or thin summer tops.

  • A4 Documents, magazines, and comic books.

  • Standard-sized tablets and small electronics.

  • A5 and A4-sized craft supplies or stationery.

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Stack of 9x12 Grey Mailing Bags
9" x 12" Grey Mailing Bags Large Letter Size (A4) – Professional Shipping for T-Shirts, Books & Documents
£2.50 – £15.36Price range: £2.50 through £15.36
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Why Thousands of UK Sellers Choose Packaging365

  • Royal Mail & Evri Ready: All our bags and boxes are tested against UK courier dimensions to help you avoid unexpected surcharges.

  • Dispatched in 24 Hours: We know your customers are waiting. Orders placed before 2 PM are processed the same day for lightning-fast UK delivery.

  • Eco-Conscious Packaging: We prioritise 100% recyclable materials, helping your small business stay green without the high price tag.

  • No-Hassle Returns: Not the right size? No problem. We offer a 30-day money-back guarantee for all unused packaging

  • Free shipping on all orders over £50
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9″ x 12″ grey mailing bags are the absolute essential for any UK reseller. Perfectly sized to match an A4 sheet, it’s the most versatile bag in our range. Whether you’re sending a single t-shirt on Vinted, a hardback book on eBay, or important business documents, this bag provides a professional, “fits-like-a-glove” finish that keeps your postage costs down.

Why Sellers Choose This Size:

  • Royal Mail Large Letter Friendly: Depending on the thickness of your item, these 9″ x 12″ grey mailing bags are designed to help you qualify for the most affordable UK postage rates.
  • Total Privacy: 9″ x 12″ grey mailing bags are 100% opaque. Your customers’ privacy is guaranteed.
  • All-Weather Protection: Completely waterproof polythene ensures your items arrive dry, even if left on a doorstep in the rain.
  • Quick-Stick Seal: The permanent self-adhesive strip saves you time during busy packing sessions—no tape required.

What Fits in This Bag?

  • Single T-shirts, leggings, or thin summer tops.
  • A4 Documents, magazines, and comic books.
  • Standard-sized tablets and small electronics.
  • A5 and A4-sized craft supplies or stationery.

Additional information

WeightN/A
Pack Size (Bags)

25, 50, 100, 200, 300, 400, 500

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Mailing Bags Size Guide

Packing a t-shirt in a grey mailing bag

Not sure which bag you need for your Vinted or eBay sales? Use our mailing bags size guide below to find the perfect fit for your items. All our bags are lightweight to help you stay within Royal Mail and Evri weight limits.

Quick Reference Chart

Bag Size (Inches)Metric Size (mm)Best For…Royal Mail Format
9 x 12″225 x 300 mmT-Shirts, Leggings, Thin Summer Dresses, A4 DocumentsLarge Letter (if < 25 mm thick)
12 x 16″300 x 400 mmThe “Workhorse”: Hoodies, Jeans, Coats, Small Shoe Boxes, Small BundlesSmall Parcel
16 x 21″400 x 525 mmWinter Coats, Boots, Larger Shoe Boxes, Multi-item “Bundles”Small/Medium Parcel

🧥 Which bag for my item?

  • T-Shirts & Tops: Most single t-shirts fit perfectly in a 9×12″ bag. If the fabric is very thin, you can often keep this under 2.5cm thick to post as a Large Letter, saving you nearly £2.00 in postage!
  • Jeans & Trousers: Adult jeans are bulky. We recommend the 12×16″ bag. It allows room for the denim to be folded without putting stress on the seams.
  • Hoodies & Knitwear: For a standard adult hoodie, go for the 12×16″. If it’s an extra-thick “oversized” hoodie or a winter coat, move up to the 16×21″.
  • Vinted Bundles: If a buyer has bought 3–5 items, the 16×21″ is your best friend. It’s heavy-duty and large enough to keep everything together in one secure package.

📏 Top Packing Tips for Sellers

  1. The “Air Squeeze”: Before sealing the bag, press down to remove excess air. This makes the parcel flatter and less likely to get caught in courier machinery.
  2. The Fold Test: If your item is right on the edge of two sizes, go for the larger one. You can always fold the excess plastic over and tape it down, but you can’t stretch a bag that’s too small!
  3. Check the Depth: Remember, Royal Mail “Large Letter” is about the thickness (25mm), not just the width. If your t-shirt is folded too “fat,” it will be charged as a Small Parcel.
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