Short answer: for most clothing orders, fold the garment neatly, optionally place it in a clear inner bag to keep it clean, and post it in an opaque, self-seal polythene mailing bag sized so the folded item lies flat with a little room for the bag to close. Use a cardboard box instead when the order includes shoes, structured or embellished items that must not be crushed, several bulky pieces, or anything with a hard component such as a boxed accessory. Put the address label on a flat, smooth panel and keep the paperwork where the customer can find it.
That simple routine covers the majority of fashion and textile orders sent by small UK sellers. This guide explains each decision in more detail: when a bag is enough, how to choose the size, whether an inner bag is worth it, how to seal and label, and which mistakes cause returns and complaints.
Contents
- Mailing bag or box: how to decide
- Choosing a mailing bag
- Getting the size right
- Inner bags: when they help
- A packing procedure for a clothing order
- Labels and paperwork
- Weight, format and postage
- Mistakes that cause complaints
- Questions sellers ask
Mailing bag or box: how to decide
Clothing is one of the few product categories that rarely needs a box. Fabric does not break, it tolerates being bent, and it is usually light. A polythene mailing bag is lighter and cheaper than a box, takes up less space on your shelf, and is quick to pack. For a T-shirt, jumper, pair of jeans, dress or set of socks, a bag is normally the right choice.
A box earns its place in a few specific situations:
- Shoes and boots. They hold their shape better in a box, and the shoe box itself should not be crushed if the customer may return them.
- Structured or embellished garments. Tailored jackets, hats, items with beading, sequins or rigid trims can be creased or damaged when a soft bag is squashed under other parcels.
- Bundles with hard items. A clothing order that also contains a boxed perfume, a belt buckle or jewellery in a presentation box is better in a box with the hard item protected.
- Gifting and presentation. Some brands use boxes for the unboxing experience. That is a branding decision rather than a protection one, and it costs more per order.
- Very bulky orders. Several heavy items can stretch a bag. A box may be easier to handle and stack.
For everything else, start with a bag. If you are not sure, pack one sample order each way and compare the weight, the time it took and how the parcel looks.
Choosing a mailing bag
Mailing bags for clothing are usually made from polythene, a flexible plastic film. The features that matter most for clothing are:
- Opacity. An opaque bag hides the contents, which matters for privacy and to avoid advertising what is inside. Our grey mailing bags are opaque grey polythene.
- A self-seal strip. A peel-and-press adhesive strip closes the bag without tape, which saves time on every order. Our grey bags have a self-seal strip.
- Water resistance. Polythene keeps rain off the contents in transit. It is not a sealed waterproof container, so do not rely on it for anything that must stay completely dry if a parcel is left in standing water.
- Size range. A wide range means you can match the bag to the garment rather than using one large bag for everything.
Coloured mailing bags are popular with fashion brands for their look. Check stock on the individual product pages in our mailing bags collection before planning around a particular colour, as availability can change.
Grey mailing bag sizes we stock
Sizes are width x length, from our current product listing. Smaller sizes come in packs of 100, larger ones in packs of 50 or 25.
| Bag size | Millimetres | Pack | Typical clothing use |
|---|---|---|---|
| 4 x 6" | 100 x 150 | 100 | Small accessories, a pair of socks |
| 6 x 9" | 165 x 230 | 100 | Underwear, small knitwear accessories |
| 9 x 12" | 230 x 300 | 100 | A folded T-shirt or vest top |
| 10 x 14" | 250 x 350 | 100 | Shirts, light jumpers |
| 12 x 16" | 305 x 405 | 100 | Jeans, hoodies |
| 13 x 19" and 14 x 21" | 330 x 485 / 350 x 525 | 100 | Heavier knitwear, two or three items |
| 15 x 18" and 16 x 21" | 381 x 457 / 405 x 535 | 100 | Coats folded, multi-item orders |
| 17 x 24" | 425 x 600 | 100 | Bulky coats, bedding |
| 20 x 26" to 28 x 34" | 508 x 660 to 700 x 850 | 50 | Large and bulky soft goods |
| 34 x 42" | 850 x 1050 | 25 | Duvets, very bulky items |
The "typical use" column is a starting point only. Folding style, fabric thickness and how many items are in the order all change the size you need, which is why it is worth testing with your own products.
Getting the size right
A bag that is too small is hard to close and puts strain on the seal. A bag that is too large lets the garment slide around, looks untidy, and can catch on sorting equipment if the excess film is not folded over. Aim for a bag that holds the folded item flat with a few centimetres spare in width and enough length to fold the flap over and seal it without stretching.
How to measure
- Fold the garment exactly as you will pack it, including any inner bag, tissue or swing tags.
- Measure the folded width and length, and note the thickness.
- Add roughly 2 to 3cm to the width so the bag slides over easily.
- Add the thickness to the length, plus room for the flap. Thick items use up length because the bag has to go over and around them.
- Pick the nearest bag size that meets both measurements.
Worked example (illustrative): a hoodie folded to 30 x 38cm and 6cm thick. Width needed is about 30 + 3 = 33cm. Length needed is about 38 + 6 + 5cm for the flap = 49cm. The 13 x 19" bag (330 x 485mm) is borderline on both, so the 14 x 21" (350 x 525mm) is the safer choice. If the hoodie folded to 28 x 35cm and 4cm thick instead, the 12 x 16" (305 x 405mm) would work with a little to spare in length after the flap.
Once you have found the right size for each product, write it down. A simple product-to-bag list on the wall of your packing area saves time and reduces mistakes when someone else packs orders.
For a broader look at mailing bag dimensions, our earlier guide to mailing bag sizes covers the size range in general terms.
Shop mailing bags and clothing bags
Inner bags: when they help
An inner bag is a clear bag the garment sits in inside the mailing bag. It is not essential, and it adds a little cost, packing time and packaging material, so use it where it solves a problem.
It helps when:
- Presentation matters. A garment in a crisp clear bag arrives looking like new stock rather than loose clothing.
- You want to keep the item clean. It protects against dust in storage and any moisture that gets into the outer bag.
- You store stock pre-bagged. If garments are bagged when they arrive from your supplier, picking and packing becomes quicker.
- Returns are common. Customers can reuse the inner bag to send items back in good condition.
Two types are common:
- Transparent OPP bags are oriented polypropylene with a glossy, high clarity finish. They give the "shop-ready" look. We stock 10 sizes from 6.5 x 9" to 18 x 22", in packs of 100. Our listing suggests 10 x 14" to 14 x 17" for folded T-shirts and light garments, and 15 x 20" and 18 x 22" for bulkier folded clothing.
- Clear polythene bags are softer, general purpose bags, sold in large sizes and boxed quantities. They suit bulkier items, storage and dust protection rather than retail presentation.
If you are not sure which suits your products, we compare the two in more detail in our guide to OPP and polythene clear bags, and the short version is: OPP for presentation, polythene for flexibility and larger items.
Whether to use an inner bag at all is a judgement about your customers and your brand. If you sell low-cost basics and your customers value minimal packaging, you may decide to skip it. If you sell higher-value items where condition on arrival matters, it is usually worth it.
A packing procedure for a clothing order
A consistent routine is faster and reduces errors. Here is a straightforward sequence for a single-garment order:
- Check the item. Confirm size, colour and condition against the order. Remove loose threads and check for marks. Most clothing returns that are not about fit are about condition or the wrong item.
- Fold consistently. Fold to the same footprint each time so it matches the bag size on your list. Fold so the logo or front faces up if you want a neat first impression.
- Add the inner bag, if used. Slide the folded garment in and seal or fold the flap.
- Add the paperwork. Put the packing slip or returns note on top of the garment inside the bag, or in a wallet on the outside (see below).
- Bag it. Slide the item into the mailing bag, push out excess air, fold the flap and press the self-seal strip firmly along its full length.
- Label it. Apply the shipping label to a flat area of the bag, away from the seal and folds.
- Weigh it. Check the weight against the postage you are buying, especially near a format limit.
For multi-item orders, stack the folded garments with the heaviest at the bottom, make sure the stack is even, and step up a bag size if the bag cannot close without stretching. If the stack is more than a few centimetres thick, consider whether a box would keep it tidier.
Labels and paperwork
Shipping labels
Most courier and marketplace systems produce labels at 4 x 6 inches (about 100 x 150mm). If you print several a day, a thermal label printer saves time and ink. We stock thermal labels on rolls in several sizes including 4 x 6", and 4 x 6" fanfold labels in stacks of 1000. These are direct thermal labels, which need a direct thermal printer. If you print on an office printer instead, A4 sheet labels come in layouts from 1 to 65 labels per sheet.
On a polythene bag, place the label on a flat, smooth area, press it down firmly from the centre outwards, and keep it clear of the seal and the folded flap so the barcode stays flat and readable.
Packing slips and returns notes
You can put paperwork inside the bag, or attach it to the outside in a clear wallet. A documents enclosed wallet is a self-adhesive clear pouch; our A6 size takes an A4 sheet folded twice. Outside wallets are useful when the courier or a warehouse needs to see the paperwork without opening the parcel. For a standard domestic clothing order, putting the slip inside is usually enough.
Weight, format and postage
Clothing is light, but bags can still end up in a dearer postage band than necessary. A few things to watch:
- Know your formats. Royal Mail's size and weight guide sets a Large Letter at up to 35.3 x 25 x 2.5cm and 750g (with a different limit for UK Tracked bought online), and a Small Parcel at up to 45 x 35 x 16cm and 2kg. A thin, folded garment may fit Large Letter limits, but many items will be Small Parcels once folded.
- Weigh real orders. Royal Mail's guide gives a pair of jeans as about 500g as a rough example. Your own garments may weigh more or less, so weigh typical packed orders once and note the result.
- Thickness counts. A soft parcel can bulge. Measure the thickest point of the packed bag, not the flat garment.
- Use the lightest packaging that does the job. A bag adds very little weight compared with a box. That is one of the main reasons sellers prefer bags for clothing.
If you sell thin items such as T-shirts, scarves or children's clothing and want to send them in the Large Letter format with a little more protection than a bag, our PIP large letter boxes are 20mm deep. The C4 size (325 x 225 x 20mm) takes an A4-sized item flat. The packed item must fit within 20mm, which rules out most knitwear.
Mistakes that cause complaints
Using one oversized bag for everything
It seems efficient to stock a single large bag, but small items rattle around, the parcel looks careless, and the loose film can snag. Stock three or four sizes that cover most of your products.
Overfilling bags
A bag stretched tight over a thick bundle can split at the seam or along a fold, particularly when it is squashed in a sorting cage. If you need to pull hard to close it, use the next size up.
Not pressing the seal properly
Self-seal strips work best when pressed firmly along their full length on a clean, dry flap. A quick pinch in the middle leaves edges that can lift. Run your hand or a flat tool along the seal.
Putting the label over the seal or a fold
A label on a crease can wrinkle, which makes barcodes harder to scan. Choose a flat panel.
Shipping damp or freshly washed items
Moisture trapped in a sealed plastic bag can cause marks or a musty smell. Make sure everything is completely dry before packing.
Forgetting the returns route
Clothing has a higher return rate than many categories. Tell customers how to return items and, if you want them to reuse your packaging, say so on the slip. A self-seal bag that is torn open roughly cannot be resealed, so some sellers include a spare strip of tape or simply explain that customers may use their own packaging.
Where this advice does not apply
This guide covers typical apparel and textiles sent within the UK. It does not cover:
- Garments with hard, sharp or fragile parts that need cushioning, which should be treated like fragile goods.
- International shipping, where customs paperwork, duties and carrier rules apply.
- Specific marketplace or brand packaging requirements, which take priority over general advice.
On disposal, polythene mailing bags are plastic film. Recycle Now's guidance on plastic bags and wrapping lists plastic bags among the films accepted at carrier bag collection points, typically at larger supermarkets. In England, GOV.UK's Simpler Recycling guidance says plastic film packaging and plastic bags will need to be collected with household plastic recycling from 31 March 2027. Until then, arrangements depend on the local council.
Questions sellers ask
What is the cheapest way to package clothes for posting?
For most garments, a correctly sized polythene mailing bag is the lowest-cost option because the bag is inexpensive, light and quick to pack. An inner bag and printed inserts add cost, so use them where they add value for your customers.
Should I use tissue paper?
Tissue is a presentation choice. It does not add meaningful protection to soft clothing. If your brand uses it, fold it neatly around the garment before it goes into the inner bag or mailing bag, and allow for the extra thickness when choosing the bag size.
Can I reuse mailing bags from my own deliveries?
You can if they are clean and undamaged and the old labels and barcodes are fully removed or covered, so they cannot be misread by sorting equipment. Many businesses prefer new bags for a consistent look.
How do I stop clothes creasing in the post?
Fold along natural lines, use a bag that fits so the garment cannot slide around, and avoid compressing items into a bag that is too small. For tailoring or garments that must arrive crease-free, a box gives more structure.
What size mailing bag do I need for a hoodie?
It depends on the fabric weight and how you fold it. Many hoodies fold to fit a 12 x 16" or 14 x 21" bag. Measure your folded hoodie as described above and test one before buying in quantity.
Do grey mailing bags need tape?
No. Our grey mailing bags have a self-seal adhesive strip, so no tape is needed to close them.
Should shoes go in a bag or a box?
A box is better. Shoes keep their shape and the original shoe box is protected. Our single wall boxes suit most single pairs; measure the shoe box and choose the next size up.
Summary
For most clothing orders: check, fold, optionally bag in a clear inner bag, post in a correctly sized opaque self-seal mailing bag, and label on a flat panel. Keep boxes for shoes, structured items and mixed orders with hard components. Record which bag fits each product, stock the handful of sizes you actually use, and weigh a few typical parcels so you buy the right postage.
