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Grey Mailing Bags | 12 x 16 Inch | Small Parcel Size

Professional A3 Shipping Solutions – 12″ x 16″ Grey Mailing Bags

What Fits in This Bag?
- Hoodies, chunky knitwear, and pairs of jeans.
- Toddler and small adult shoe boxes.
- Handbags and larger accessories.
- Standard board games or multiple thin clothing items.
E-Commerce: Ideal for eBay, Vinted, Depop, and Etsy sellers shipping non-fragile items.

Also available in our mixed size packs

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Professional A3 Shipping Solutions – 12″ x 16″ Grey Mailing Bags

When the 9×12 is just a bit too tight, the 12″ x 16″ (A3 equivalent) Medium Grey Mailing Bags are your go-to hero. This is our most popular “Medium” size, offering the extra room needed for bulkier clothing items and small shoe boxes. Lightweight but incredibly tough, these bags allow you to ship heavier textiles without the fear of the packaging splitting during transit.

Why Sellers Choose This Size:

Heavy Duty Strength: Our co-extruded polythene is puncture-resistant, meaning sharp corners on games or boxes won’t poke through. The “Bundle” Bag: The perfect size for multi-item Vinted bundles that are too large for a standard mailer. Professional Aesthetic: The clean, matte grey finish gives your brand a professional look compared to flimsy, transparent alternatives. Tamper-Evident Security: Once the permanent seal is shut, it cannot be opened without leaving visible signs of tampering.

Perfect For:

Hoodies, chunky knitwear, and pairs of jeans. Toddler and small adult shoe boxes. Handbags and larger accessories. Standard board games or multiple thin clothing items.

Also available in our mixed size packs

Technical Specifications:

Size: 12 16 inches (300mm x 400mm approx)
Material: 100% Recyclable LDPE (60 Micron thickness)
Closure: Permanent Self-Seal Strip
Color: Professional Opaque Grey

The Packaging365 Guarantee: Join over 5,000 UK resellers who trust us for their supplies. Order before 1 PM for same-day dispatch and take advantage of our wholesale rates—even on smaller packs!

Additional information

Weight	0.275 kg

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Mailing Bags Size Guide

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 mm	T-Shirts, Leggings, Thin Summer Dresses, A4 Documents	Large Letter (if < 25 mm thick)
12 x 16″	300 x 400 mm	The “Workhorse”: Hoodies, Jeans, Coats, Small Shoe Boxes, Small Bundles	Small Parcel
16 x 21″	400 x 525 mm	Winter 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

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.
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!
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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Grey Mailing Bags | 12 x 16 Inch | Small Parcel Size