Grey Mailing Bags 15×18" (381×457 mm) are a reliable step up for bulkier apparel, soft homeware and medium boxed goods. Made from tough 60 µm co-extruded, 100% recycled LDPE, these self-seal postal bags are moisture-proof / water-resistant, fully opaque for privacy and recyclable via UK soft-plastic schemes. Sized to keep many orders within Royal Mail Small Parcel when packed efficiently, and ideal for eBay, Amazon and Shopify dispatch.
Need a different fit? See all Grey sizes or browse the full Mailing Bags range. Prefer brand colour? Explore Coloured Mailing Bags.
Why this 15×18" size?
When 12×16" starts to feel tight, 15×18" adds the depth and width needed for coats, thick hoodies, knitwear sets and multi-item bundles — without jumping straight to heavy box-only shipments. The neutral grey film hides contents and resists scuffs for a clean, consistent delivery look.
Who it’s ideal for
- Apparel & fashion: winter hoodies, jogger sets, stacked jumpers, light jackets/gilets.
- Home & textiles: cushion covers, throws, towel sets, bedding in sleeves.
- Retail & gifts: beauty gift sets, compact shoe boxes, accessory kits.
- Marketplaces: dependable size for eBay, Amazon and Shopify daily dispatch.
Fit & packing guidance
- Best fit: coats, bulky knitwear, hoodie + jeans, stacked apparel, towel sets, boxed kits.
- If it strains at the seal: step up to 17×24" for bedding and big bundles.
- If it’s roomy: step down to 12×16" to cut void space and postage.
- Corner care: pad sharp box edges; use a light inner sleeve for dusty items.
- Press out air: flatten before sealing so labels sit flat and sacks stack neatly.
Key benefits
- Fast self-seal, tamper-evident closure — no tape needed for most orders.
- 60 µm co-extruded film — resists tears, splits and punctures in courier handling.
- Moisture-proof / water-resistant outer for wet routes.
- Fully opaque grey — privacy and a professional look on arrival.
- Lightweight — helps keep parcels in cheaper bands vs cardboard boxes.
- Recyclable LDPE (code 4) — remove glue strip before recycling.
Eco & materials
Material: 100% recycled LDPE (code 4), co-extruded for strength and opacity. Recyclable at many UK supermarket soft-plastic return points. Not biodegradable or compostable.
Strength & protection
The 60 µm film gives dependable tear and puncture resistance on bulky packs. The permanent adhesive creates a tamper-evident bond once pressed, protecting contents through warehouse and courier networks.
Storage & performance
Store flat at 13–21 °C away from heat/sunlight. Let cold stock reach room temperature before use for consistent seal strength.
Lightweight = lower postage
Mailing bags reduce dead weight and parcel size compared with boxes, helping orders stay within Royal Mail Small Parcel and lower courier tiers where appropriate.
Size comparison (find your best fit)
| Size | Inches | Millimetres | Typical fit |
|---|---|---|---|
| Step down | 12×16" | 305×406 mm | Hoodies, jeans, A4+ bundles, small boxes |
| This page | 15×18" | 381×457 mm | Coats, knit sets, multi-item apparel, towel sets, gift boxes |
| Step up | 17×24" | 432×610 mm | Bedding, bulky textiles, larger boxed goods |
Buying guide: 12×16", 15×18" or 17×24"?
12×16" handles hoodies and A4+ packs with ease. Choose 15×18" for coats, stacked apparel and boxed gifts — the everyday “bulky apparel” workhorse. For bedding and very large bundles, 17×24" keeps the seal clean and stress-free.
Common searches
15×18 mailing bags • grey poly mailers • waterproof postal bags • recyclable mailing bags UK • Royal Mail Small Parcel packaging • bulk grey mailing bags • eBay and Amazon shipping bags
| Material | LDPE (code 4) |
| Size | 15x18 Inch (381x457 mm) |
| Color | Grey |
| Closure | Peel-and-Seal (Permanent) |
| Recyclability | Return to Supermarket Soft-Plastic Points |
| Thickness | 60 µm |
| Water Protection | Water-Resistant |
What fits in a 15×18" grey mailing bag?
Is 15×18" okay for Royal Mail Small Parcel?
Are grey mailing bags waterproof?
Are 15×18" grey mailing bags recyclable?
How strong are these 15×18" mailers?
When should I choose 12×16" vs 15×18"?
When should I step up to 17×24"?
Are these bags fully opaque for privacy?
How should I store 15×18" grey mailing bags?
Do I need extra tape with 15×18" bags?
Royal Mail 24 Tracked
Dispatched same day if ordered before 5 pm Monday to Friday. Please allow up to 1-2 days for delivery.
£1.99
DPD Next Day
Dispatched same day if ordered before 3 pm Monday to Thursday. Not available to Scottish Highlands & Islands.
£4.99
Free on orders over £100