Stiff envelopes that keep cards flat in the post.
Typical price
£10 to £18
Why we pick it
- Typical price
- £10 to £18
- Works with
A sleeved and top-loaded card in a rigid mailer stays flat through sorting machines and usually ships as a Large Letter, which costs far less than a parcel.
Good for
- Prints, photos and trading cards
- Flat items that must not bend
- Trading cards, prints and photos
- Keeping a card parcel a Large Letter
Not for
- Any clothing sale
- Bulky or soft items
Our approved alternative for the same job: Kraft padded envelopes, D/1, 100 pack
The guide
Each step in the order you'll need it.
Who should keep C6 board-backed mailers in stock
Card sellers posting one to a handful of toploaded singles use these, and so does anyone sending photos, prints or postcards. Vinted, eBay and Whatnot buyers all expect a card to arrive flat.
A 100 pack at £10 to £18 covers a busy month for a breaker and a few months at a casual pace. If most of your orders are lots of 50 cards or more, a small box serves you better.
Inner size, board and flap on a C6 mailer
C6 is the ISO paper size of 114 by 162 mm, and a C6 envelope fits a 3 by 4 inch toploader with room to spare. Read the listed inner size, as some board-backed mailers are cut slightly smaller than true C6.
Choose a full board back and a board front, or at least a stiff board back with a printed "Please do not bend" line. A peel-and-seal flap saves you reaching for tape on every order.
The finished mailer has to fit within Royal Mail's Large Letter limits for thickness and weight to go at that price. A toploader plus a team bag sits well inside most thickness limits, but double stacks may not; Royal Mail's current size guide has the figures.
Packing a card order in under a minute
Sleeve the card, load it into a toploader, seal the toploader in a team bag, then slide the bundle into the mailer. For two or three cards, lay the toploaders side by side, never stacked loose, and tape them together with painter's tape.
Stick the label on the front, away from the flap, and weigh the finished envelope on a pocket scale before you buy postage. A 500 g precision pocket scale reads light card orders to the gram.
Kit for this step
Padded envelopes, boxes and poly bags for cards
Kraft padded envelopes, D/1, 100 pack, are the fallback. They cushion bumps, but the bubble lining flexes, so add a piece of board for any toploaded card.
Small single-wall boxes, 25 pack, give bigger lots crush protection an envelope cannot match. Switch to a box once a card order outgrows the Large Letter limits.
Grey mailing bags, 10 x 14 in, 100 pack, suit clothing but leave cards free to bend, so keep them away from your card stock.
Kit for this step
Mailer cost against a £3 card sale
At £10 to £18 per 100, the mailer adds about 10p to 18p per order. With a sleeve, toploader and team bag, a full card pack still comes in well under 50p before postage.
That leaves room on a £3 to £5 card sale. Track your costs per order for a month to see whether a bigger pack brings the mailer price down enough to pay off.
Common mistakes
Each one costs you money or reviews, and each has a fix.
- Toploader every card before it goes in. A bare card in a mailer bends at the corners.
- Two toploaders stacked on top of each other can push the envelope past Large Letter thickness; lay them side by side or check Royal Mail's current size guide.
- A label over the flap means the buyer tears through it. Place it on the plain front.
- Guessed weights risk underpaid postage and a fee for the buyer, so weigh each finished mailer on a scale.
- Mailers cut smaller than true C6 jam toploaders in tight; check the inner dimensions before you order a big pack.
Ranked in
Where it places in our rankings, and the reason.
- #4Ranked #4Best mailing bags for VintedOnly worth a place if your Vinted shop also sells prints, postcards or trading cards. The board backing keeps a flat item from bending in a sorting machine, and the C6 size suits one card or a small print.
- #3Ranked #3Best mailing bags for Vinted and card mailersKeeps cards and prints flat, and usually ships as a Large Letter.
Setups that use it
Complete kits this product is part of.
Guides that use it
Step-by-step help where this product does a job.
Questions
Does a toploaded card in a C6 mailer go as a Large Letter?
Often it does, if the finished envelope meets Royal Mail's Large Letter size, thickness and weight limits. Confirm against Royal Mail's current size guide before you rely on it.
How many toploaders fit in one C6 mailer?
Two side by side fit in most true C6 mailers. Stacking more raises the thickness, so measure the result.
Do I need a padded envelope instead?
Not for single cards. Bends do more damage to a card than knocks, and the board stops bends. Use padding for odd-shaped items.
Can I write "Do not bend" on a plain envelope instead?
You can, but sorting machines ignore it. The board keeps the card flat.
Will a C6 mailer fit a graded slab?
No. A slab is too thick and too long for C6. Post slabs in a small box with padding.
Alternatives
Other picks for the same job, cheaper and pricier.
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 AmazonKraft padded envelopes, D/1, 100 pack
Enough padding for a lipstick, a small figure or a sealed booster pack, with no box to fold.
Typical price£14 to £22
See on AmazonRecyclable paper mailing bags, 100 pack
Costs about twice as much per bag as grey poly, and buyers notice the paper. It suits vintage and handmade shops that sell on character.
Typical price£18 to £28
See on Amazon