Shipping
Shipping box sizes: how to pick one that doesn't cost extra
The right shipping box size is the smallest box that holds your product with padding on every side. Sizes are written length x width x height in inches, measured on the inside, and the carrier bills on the outside size, so every spare inch of box costs you money.
There's no single standard list. Stock sizes differ between suppliers, which is why plenty of brands end up shipping a small product in a box twice its size.
By Talha LoneUpdated
How shipping box sizes are written
Box sizes are always length x width x height, and those numbers describe the inside of the box. Length and width are the sides of the opening, and height runs from the opening to the bottom. Carriers measure the outside, which is bigger by the thickness of the board on each wall. How to measure a box explains the order in full.
| Board | Wall thickness | Inside 10 x 8 x 4 becomes (outside) |
|---|---|---|
| E-flute corrugated | Roughly 1/16 inch | Roughly 10 1/8 x 8 1/8 x 4 1/8 |
| B-flute corrugated | Roughly 1/8 inch | Roughly 10 1/4 x 8 1/4 x 4 1/4 |
Why box size changes your postage
Carriers bill whichever is greater: the actual weight or the dimensional weight. UPS calculates dimensional weight as length x width x height divided by 139 on daily rates, then rounds up to the next pound, per its shipping dimensions and weight guide. Other carriers use their own divisors.
| Outside size | Cubic inches | Divided by 139 | Billed as |
|---|---|---|---|
| 10 x 8 x 4 in | 320 | 2.3 | 3 lb |
| 12 x 10 x 8 in | 960 | 6.9 | 7 lb |
Same product, same weight, more than double the billed weight. Dimensional weight means you can pay to ship air. Quite a lot of it, if the box is too big. We draw the box around the product, so the air stays out.
Carrier size limits
Most parcels can't go over 108 inches in length and girth combined under the USPS Domestic Mail Manual. Girth is 2 x width + 2 x height, taken around the thickest part. Most product brands never get near that limit, but it matters for tubes and long items.
How to pick the size
- Measure the product at its widest point on each side, in the order it sits in the box.
- Add what goes in with it: an insert, tissue, a card.
- Leave room for padding on every side, then pack a test box and shake it.
- Compare two sizes with the dimensional weight sum above before you commit.
- Order custom once your sizes settle. One size drawn to your product usually beats three near-fits.
Which box you pick matters as much as the size. A mailer goes in the mail with nothing around it, a shipping box suits heavy or mixed orders, and a retail carton belongs on a shelf. Your shipping box and your retail box should be different boxes: a delivery truck isn't a shelf. See custom mailer boxes, custom shipping boxes and custom cardboard boxes.
When not to go custom
- Your product sizes change every month. Stock sizes plus paper fill cost less than redrawing a box each time.
- You ship under 50 a design. Custom boxes start at 50 units per design.
- You need them this week. Production takes 10–12 days from proof approval, plus shipping.
If you ship the same product every week, send the length x width x height, or a photo of it on a ruler. Structural design is $0, and we add clearance on the dieline, so don't add it yourself.
Frequently asked questions
What are standard shipping box sizes?
There's no single standard. Sizes differ between suppliers and are written length x width x height on the inside. Pick the smallest box that fits your product with padding on every side.
How do I choose the right shipping box size?
Measure your product at its widest point on each side, add anything that goes in with it, leave room for padding and test a packed box. Then compare dimensional weight for two sizes.
Do shipping boxes use inside or outside dimensions?
Box makers use inside dimensions because that's the space your product needs. Carriers bill on the outside of the sealed parcel, which is slightly bigger.
How does box size affect shipping cost?
Carriers bill the greater of actual weight and dimensional weight. UPS uses length x width x height divided by 139 on daily rates, rounded up to the next pound, so a bigger box can bill as more than the product weighs.
What is the maximum shipping box size?
Most USPS parcels can't exceed 108 inches in length and girth combined. Girth is 2 x width + 2 x height. Other carriers set their own limits.
Can I get a shipping box made to my product's size?
Yes. Custom boxes start at 50 units per design, structural design is $0 and production takes 10–12 days from proof approval.