The Ultimate Guide to Paper Mailing Bags
Choose the right bag in under a minute — then see why paper is the smarter, more sustainable choice.
Paper mailing bags are the plastic-free way to post soft, non-fragile goods — clothing, textiles, books, prints and accessories — in packaging that's recyclable at kerbside and kinder to the planet. But "paper mailing bag" isn't one product. There are four different constructions, each built for a different kind of item, and picking the right one is the difference between a neat, protective parcel and wasted material or damaged goods.
This guide does two things: it helps you choose the right bag in under a minute, then explains why paper is the smarter, more sustainable choice. If you already know what you're sending, jump straight to the type that fits.
Which paper mailing bag do you need?
There are four styles, and they form a simple ladder from slimmest to bulkiest. Match the bag to the shape and volume of what you're sending.
1. Wallet / Flat mailers — for slim, letterbox-sized items
The simplest style: a flat, envelope-style bag with no gusset and a variable-depth fold, so it stays low-profile and posts through a standard letterbox. Ideal for documents, prints, a single folded garment, or slim accessories where you want the lowest possible postage.
Best for: documents, prints, single T-shirts, slimline accessories, letterbox delivery
Postage sweet spot: Large Letter
→ Shop letterbox-friendly paper mailing bags
2. Bottom gusset bags — for slim items that need a little depth
These add a single gusset at the base, so the bag opens up a little from the bottom while the sides stay flat. A neat step up from a flat wallet when your item needs a touch more depth — but not much extra width.
Best for: accessories, small apparel items, slim soft goods, single garments with a little depth
Postage sweet spot: Large Letter to Small Parcel
→ Shop bottom gusset paper mailing bags
3. Side gusset bags — for folded clothing and soft goods
These expand at both sides with a flat, folded (non-gusseted) bottom, opening out across the whole bag for more room while still folding down neatly when part-filled. A great all-rounder for apparel and soft goods with a bit more bulk.
Best for: folded clothing, knitwear, soft accessories, multi-item apparel orders
Postage sweet spot: Small to Medium Parcel
→ Shop side gusset paper mailing bags
4. Block bottom bags — for bulky items or multiple items together
The most box-like option: a flat, boxy base plus dual side gussets, so the bag stands up and opens out to hold volume. Choose this when you're sending several items at once or something with real bulk.
Best for: bulky orders, multiple items, chunky knitwear, homeware
Postage sweet spot: Small to Large Parcel
→ Shop block bottom paper mailing bagsAt a glance: which type, when?
| Bag style | Shape | Capacity | Best for | Typical postage |
|---|---|---|---|---|
| Wallet / Flat | No gusset, flat | Lowest | Documents, prints, single garments | Large Letter |
| Bottom gusset | Base gusset, flat sides | Low | Accessories, slim soft goods | Large Letter / Small Parcel |
| Side gusset | Side gussets, flat bottom | Medium | Folded clothing, soft goods | Small / Medium Parcel |
| Block bottom | Side gussets + block bottom | Highest | Bulky or multiple items | Small–Large Parcel |
Not sure? Order free samples and test the fit with your own products before you commit to a size.
Getting the size and postage right
Choosing the right style is half the job; the right size keeps your postage costs down and your parcels tidy.
- Measure your product at its widest, tallest and deepest points, then allow a little room for the closure fold. Aim to fill the bag without straining the seams.
- Post as a Large Letter where you can. If your item fits within Royal Mail's Large Letter dimensions, a wallet or bottom gusset bag can keep you in the cheapest bracket. Shop by size:
- Letterbox delivery improves the customer experience and cuts failed deliveries — if your product is slim, choose a letterbox-friendly bag.
- Sending something heavier or with sharp corners? Step up to a 2-ply bag for extra strength, or consider a paper padded mailing bag for light cushioning.
Our ranges
Priory Elements EcoMailingBags™
Priory Elements EcoMailingBags™ are our own-brand, plastic-free alternative to poly mailers. Made from strong kraft paper with a peel-and-seal closure, they're 100% recyclable, biodegradable and made from sustainably sourced materials. Available across all four constructions and in letterbox-friendly sizes, they carry our signature endangered-animal designs — turning your packaging into a talking point for your brand and the planet.
Plain paper mailing bags
Plain paper mailing bags offer the same protection and recyclability in a clean, unbranded finish. A cost-effective choice for businesses that want a professional, minimalist look, or that add their own branding with a printed label or tape.
Custom printed paper mailing bags
Custom paper mailing bags make your packaging your best marketing asset. Print up to two colours on both sides or four colours on one side, with eye-catching graphics or your sustainability story front and centre. Your packaging is the one piece of marketing with a 100% open rate — make it count.
Why paper? The sustainability case
Switching from plastic to paper mailers is one of the simplest, highest-impact changes an e-commerce business can make. Our independent life-cycle analysis compared paper mailing bags with traditional PE poly mailers, and the results are clear:
- Up to 66% lower carbon emissions — switching from virgin PE mailers to unbleached paper cuts carbon by 49%, rising to 66% with a 100gsm unbleached paper bag.
- A negative biogenic carbon footprint — paper bags help absorb more CO₂ than they emit, where virgin PE adds roughly +54.8kg CO₂ per unit.
- 32% lower acidification potential and up to 74% lower eutrophication potential, meaning cleaner air and healthier water systems.
- 27% lower photochemical ozone creation potential (POCP) — less smog-forming pollution.
→ Read the full science behind paper vs. plastic
Recyclability: paper wins at kerbside
Recyclability is where paper really pulls ahead. UK paper packaging recycling rates reached around 90% in 2020 (Confederation of Paper Industries), and paper mailing bags go straight into standard household paper recycling. By contrast, only a small fraction of LDPE plastic film is recycled — UK plastic packaging recycling sat at roughly 40%, with LDPE far lower — because most kerbside schemes don't accept soft plastics. Choosing paper means your customers can recycle their packaging easily, at home, with no special collection.
→ Compare paper vs. poly mailing bags in detail
Trusted by brands that take sustainability seriously
Paper mailing bags are now the default for many of the world's most recognisable retailers — including Nike, H&M, Zara, M&S (The Sports Edit) and Bamboo Clothing — proof that plastic-free packaging works at every scale.
Frequently asked questions
Are paper mailing bags waterproof?
They're shower-resistant rather than fully waterproof — kraft paper handles normal transit and light moisture well. For items that are especially moisture-sensitive, add an inner paper or glassine wrap, or choose a 2-ply bag.
Can I send fragile items in a paper mailing bag?
Paper mailing bags are designed for non-fragile, soft or semi-rigid goods. For anything breakable, use a paper padded mailing bag or a cardboard box with protective void fill.
Which bag is cheapest to post?
Whichever keeps you in the lowest postage bracket for your item. Slim items in a wallet or bottom gusset bag can often go as a Large Letter — the cheapest option. Shop Large Letter bags.
Can I get them printed with my logo?
Yes — see custom printed paper mailing bags for branding options.
How do I know what size I need?
Measure your product's width, height and depth, add room for the fold, and order free samples to test the fit.
Ready to make the switch?
Browse the full paper mailing bags range, or start with the style that fits what you send:
Still unsure? Order free samples or get in touch — we're happy to help you find the perfect fit.
