Thin boxes about an inch deep for small, flat items.
Typical price
$40 to $60
Why we pick it
- Typical price
- $40 to $60
- Works with
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.
Good for
- Jewelry, coins and graded cards
- Keeping packages under 1 lb
Not for
- Anything thicker than about an inch when packed
Our approved alternative for the same job: Small corrugated boxes, 25 pack
The guide
Each step in the order you'll need it.
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.
Kit for this step
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
Each one costs you money or reviews, and each has a fix.
- 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.
Ranked in
Where it places in our rankings, and the reason.
Setups that use it
Complete kits this product is part of.
Questions
Straight answers to what sellers ask about this.
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.
Alternatives
Other picks for the same job, cheaper and pricier.
Small jewelry boxes, 50 pack
A foam insert holds the piece still in the box. The box fits inside a padded envelope, so most orders still ship as a light, thin package.
Typical price$10 to $16
See on AmazonSmall corrugated boxes, 25 pack
Use these for boxed toys and beauty sets that a poly mailer would crush, when double-wall board costs more than you need.
Typical price$12 to $25
See on Amazon12-inch LP record mailers, 10 pack
A folding corrugated mailer holds one to three 12-inch records flat, so corners and jacket seams survive the sorting belts. Buy them if you sell vinyl every week; for a box set or a stack of records, use a box with bubble wrap.
Typical price$25 to $40
See on AmazonDie-cut mailer boxes, 50 pack
These fold flat, lock with tabs and keep a small item snug, so it ships in a compact package. Pick a depth that fits your usual item with a little padding.
Typical price$25 to $45
See on Amazon