# Flat mailer boxes, 50 pack > Thin boxes about an inch deep for small, flat items. - Boxes, Starter pick - Typical UK price: $40 to $60 (a typical band, not a live price) - Platforms: Whatnot, eBay, Vinted, TikTok Shop, Depop, Etsy - Orders a week: 0–2000 - Checked October 7, 2026 A slim box protects a small item better than an envelope and weighs only a few ounces, which keeps it in a low USPS Ground Advantage weight tier. Weigh the packed box before you buy the label. ## Kit rankings - #4 in [Best shipping boxes for US home sellers](https://sellersetups.com/us/kit/boxes) ## Setups - [Comic back-issue room for Whatnot shows and eBay](https://sellersetups.com/us/setups/comic-back-issues-live): Long boxes, bags and boards, an overhead phone and board-stiffened mailers for selling back issues live in the evening and on eBay in between. - [Handmade silver jewelry studio for Etsy and Depop](https://sellersetups.com/us/setups/etsy-silver-jewellery-maker): A gram scale, a light box, gift boxes and small flat mailers for makers selling their own rings, studs and pendants from a bench in the corner. ## Small, flat items an envelope would crush Use flat mailer boxes for small, flat items an envelope would crush: a lipstick or palette, earrings, a few graded cards, a paperback, coins in capsules. At a handful of orders a week on Etsy, eBay or Mercari, a 50 pack lasts a few months. At dozens a day, buy a case from a packaging supplier to bring the unit cost down. ## Outer size and board type USPS treats a rigid box as a package, not a letter or flat. Check USPS's current size and shape rules. Ground Advantage prices go by weight and zone, so a light box costs less to ship whatever its depth. Confirm the listed size is the outside measurement. Look for sizes around 9 × 6 × 1 inches or similar, which fit most small orders and stay light. Single-wall corrugated board with a tuck-in lid and a peel-and-seal strip works best. Choose white board for gifts and beauty, brown kraft for everything else. ## Packing a flat mailer box Lay a sheet of tissue in the base, place the item flat and fill gaps with a little paper so nothing slides when you tip the box. Keep fill below the rim so the lid closes flat. Close the lid and weigh the box on your shipping scale to the ounce before you buy a label on Pirate Ship, eBay or Etsy. Print a 4 × 6 label and fold any overhang onto the back, or use a smaller label on a narrow lid. Store flat-packed boxes upright near your bench so they stay square. ## Other packaging and when to switch Small corrugated boxes are the fallback and fit anything too deep for a flat mailer. Move to them once the item no longer lies flat. Die-cut mailer boxes take bulkier items such as figures or sneakers. Kraft padded envelopes cost less for soft or unbreakable items like accessories. Card mailers weigh less for a single card in a toploader. For gifts, put a small jewelry box inside this box. ## Box cost against a damaged order A 50 pack at $40 to $60 works out at about 80 cents to $1.20 a box. That costs more than a padded envelope but less than a refund on a crushed item. Weigh each packed box until you know which tier your usual items land in. ## Common mistakes - Boxes listed by inside size can arrive larger than you expect. Check the outside dimensions. - Heavy void fill bows the lid and adds weight; one layer of tissue or paper is enough. - Guessing the weight can bring a postage-due notice. Weigh the packed box. - Several hardcovers can push the box into a higher weight tier. - Flat packs stored on their side under weight warp. Stack them flat, or upright and loose. ## Questions ### Can these ship as a letter or flat? No. Merchandise in a box ships as a package. USPS Ground Advantage is the usual low-cost service for light boxes. ### Do I need tape? Many slim boxes have a peel-and-seal strip. If yours do not, one short strip of tape over the lid holds it. ### White or brown board? White suits beauty, jewelry and gift orders where the unboxing counts. Brown kraft hides scuffs from sorting machines. ### Can I ship trading cards in these? Yes. A toploaded card or a small stack in a team bag sits flat inside and gets more crush protection than a card mailer. ### Should I add void fill? A sheet of tissue or a little paper does it. Bulky fill bows the lid.