Grey Mailing Bags 15×18" (381×457 mm) — roomy, fast to pack, and built for daily dispatch

Grey mailing bags 15×18" (381×457 mm) give you extra capacity without jumping to heavy, box-only shipments. Made from tough 60-micron LDPE (low-density polyethylene), these self-seal postal bags are moisture-proof (water-resistant), opaque for privacy, and quick to close with a peel-and-seal strip. The 15×18" footprint sits between A3 and A2 — ideal for bulkier apparel, soft homewares, and boxed goods that don’t need a rigid carton.

Need a different fit? See all sizes or browse the full Mailing Bags range.

Why this 15×18" size?

It’s the step up that keeps orders moving when 12×16" starts to feel tight. You gain space for coats, thick knitwear, multi-item clothing bundles, and larger boxed products, but you still benefit from lightweight postage and fast packing. The neutral grey finish looks tidy, hides contents, and keeps parcels consistent across busy dispatch days.

Real use examples (what typically fits)

• Apparel: winter coats, hoodies and jogger sets, stacked jumpers, bulkier knitwear.
• Home & textiles: cushion covers, throws, towel sets, bedding in retail sleeves.
• Boxed goods: shoe boxes (smaller styles), beauty gift sets, accessories in inner cartons.
• Print & kits: catalogues, brochures, subscription kits, DIY bundles with inner wrap.

Size calculator tip (pick the best fit first time)

Measure the longest edge (L), shortest edge (W) and thickness (H) of the packed item. A flat mailer fits roughly: Item L ≤ Bag length and Item W + H ≤ Bag width. Add a small allowance for the self-seal fold. If the parcel feels bulky or rigid at the corners, move up a size for a clean seal and less stress on the film.

Fit guidance

• Best fit: coats, hoodies + joggers, stacked apparel, towel sets, boxed beauty kits, small shoe boxes.
• Too tight? If 15×18" strains at the seal, step up to 17×24" for bulky textiles.
• Too roomy? For single hoodies or jeans, step down to 12×16" to reduce void space and postage.

Key benefits

• Self-seal speed: peel, press, and you’re done — ideal for busy benches.
• 60-micron co-extruded film: helps resist tears, splits and scuffs through conveyors and cage moves.
• Moisture-proof / water-resistant outer: extra peace of mind in rain and on damp surfaces.
• Opaque grey: privacy for customers; clean, professional presentation.
• Lightweight vs boxes: save on postage where a rigid carton isn’t required.
• Recyclable LDPE: remove the glue strip before recycling.

Specifications

Eco & Materials

Material: 100% recycled LDPE (resin code 4), co-extruded for strength and opacity. Recyclable in many UK schemes — please remove the adhesive strip first. These bags are not biodegradable or compostable.

Strength & Protection

60-micron co-extruded film is puncture- and tear-resistant and moisture-proof. The self-seal, tamper-evident all-season adhesive forms a permanent bond once pressed, helping contents stay secure from dispatch to delivery.

Storage & Performance

Store bags at 13–21 °C and out of direct heat or sunlight. Let cold stock acclimatise to room temperature before use to maintain adhesive performance.

Lightweight = Lower Postage

Our recycled LDPE mailers are exceptionally lightweight, helping you keep parcels in lower weight bands versus boxes — a simple way to cut postal costs without losing protection.

Common mistakes (avoid returns and re-packs)

• Overfilling: if the seal struggles to meet, go up a size; a stressed seam invites tearing.
• Sharp corners: pad or round box corners to reduce punctures.
• Trapped air: press out air before sealing — flatter parcels stack better and can ship cheaper.
• Label placement: apply labels on a clean, flat section so scanners read first time.

Size comparison (choose the right bag for each order)

Cross-links (find the perfect fit)

Need a tighter fit? Try 12×16". Sending bigger items? Choose 17×24". For tape, wallets and boxes, see Packaging Tape, Document Wallets and Cardboard Boxes. Explore all colours and sizes in the Mailing Bags collection.

FAQs

Is 15×18" big enough for coats and stacked apparel?

Yes — it’s designed for bulkier clothing, soft homewares and mid-sized boxed goods. If the seal strains, step up to 17×24".

Are these bags waterproof?

They’re moisture-proof / water-resistant and help protect against rain and splashes. For very wet routes, use an inner sleeve.

Are they recyclable or biodegradable?

They are recyclable in many UK schemes — please remove the glue strip first. They are not biodegradable or compostable.

What thickness is this size?

This 15×18" bag is produced at 60 µm for strength with low weight.

How should I store them?

Keep stock between 13–21 °C and out of direct heat/sunlight. Let cold packs acclimatise before use.