How to build kids' clothes bundles that sell, and the baby items safety charities tell parents not to buy second-hand: car seats, cot mattresses and more.
Updated 6 October 2026
Before you start
How to build kids' clothes bundles that sell, and the baby items safety charities tell parents not to buy second-hand: car seats, cot mattresses and more.
Outgrown kids' clothes are some of the easiest things to resell: they are barely worn, sized by age, and parents buy them in bundles. A few baby items carry risk instead, with safety charities advising parents against buying them second-hand.
Safety points come from RoSPA, the Lullaby Trust and gov.uk, checked 6 October 2026. Treat it as general guidance; it is no legal ruling on any item.
Kit for this
The products this guide uses, with typical UK prices.
Grey mailing bags, 10 x 14 in, 100 pack
Self-seal poly bags add almost no weight, so a single garment posts as a small parcel. You can't see through the opaque grey film, and a label lies flat on it.
Typical price£8 to £13
See on Amazon
Clear stackable 32 L tubs, 4 pack
Label each tub with a shelf code and record the code against the listing. A sale then tells you which tub to open.
Typical price£30 to £45
See on Amazon30 kg digital postal scale
Covers the parcels most home sellers ship, up to 30 kg. Choose it when the 40 kg scale is out of stock.
Typical price£12 to £20
See on AmazonThe guide
Each step in the order you'll need it.
Build bundles by age and season
Group by one size and one season: "Girls 2 to 3 years, 12 summer pieces". A parent shopping for next summer searches by size, and mixed sizes put them off.
Lay the bundle flat for one overview photo, then add close-ups of the labels and any stain. Count the pieces in the title so buyers can work out the price per item.
Price and post a bundle
Bundles of plain basics go cheap per item; named brands, coats and school uniform hold more. Pull the best two or three pieces out to list alone if they would sell on their own.
Weigh the bundle in its bag before you list it. Twelve summer pieces often fit a small parcel, but winter coats push it into a heavier band.
Car seats: sell new or not at all
RoSPA advises never buying a second-hand car seat unless you know its full history. A crash or a drop can damage it in ways you cannot see.
As a seller you cannot prove that history to a stranger. Recycle an old seat through a retailer scheme or your council instead of listing it.
Cot mattresses, bumpers and nests
The Lullaby Trust advises a new mattress for each baby where possible. A used one should be firm, flat, a good fit, free of tears and water damage, and carry a fire-resistant label: hard to show in photos.
The Lullaby Trust also advises against cot bumpers and baby pods or nests, since soft sides can cover a baby's face. Leave these out of bundles.
Nightwear and hood cords
The Nightwear (Safety) Regulations exempt second-hand nightwear, so used pyjamas can go in a bundle. Check the fabric for wear all the same.
For hood cords, UK rules ban a child's hood fastened with a drawstring. Pull the cord out of any old hoodie before you sell it, and say so in the listing.
Check recalls before you list
Search the product name on gov.uk's product safety alerts and recalls list before you list a pushchair, sling, high chair or toy. Send a recalled item back through the recall.
RoSPA tells buyers of second-hand toys to look for a CE or UKCA mark and the instructions. Include both in your photos when you have them.
Items with no clear rule
We found no official UK guidance on second-hand breast pumps, bottle teats or dummies. Most buyers want these new for hygiene, so they sell poorly used.
If you buy kids' clothes in bulk to resell, you are trading: the HMRC rules and consumer rights apply to you. Read our HMRC guide.
Checklist
Run through it before each one goes out.
- 1Bundle one size and one season
- 2Count pieces in the title
- 3Weigh the bundle in its bag
- 4Recycle old car seats, never list them
- 5Leave out bumpers, nests and used mattresses
- 6Remove hood cords and check recalls
Setups
Complete kits for one kind of seller, costed and laid out.
Questions
Can I sell a second-hand car seat in the UK?
RoSPA advises against buying one unless you know its full history. A buyer cannot check that, so recycle it instead.
Can I sell a used cot mattress?
The Lullaby Trust advises a new mattress for each baby where possible. Sell the cot, and leave the mattress out.
How many items should be in a kids' clothes bundle?
Enough to fill one parcel band. Ten to fifteen summer pieces often fit a small parcel; weigh it before you list.
Can I sell second-hand children's pyjamas?
Yes. The nightwear safety rules exempt second-hand nightwear. Check for wear and wash them first.
Do second-hand toys need a UKCA mark?
RoSPA tells buyers to look for a CE or UKCA mark. Show it in the photos if the toy has one, and check the recall list.
Can I sell a pushchair or pram?
Yes, after checking the recall list for its model. Our guide to posting bulky items covers packing one.