Box Sizes in CM and MM: Shipping Box Conversion Chart
To convert a box size from inches to cm, multiply each side by 2.54. A 12 x 12 x 12 inch box is 30.5 x 30.5 x 30.5 cm, a 12 x 9 x 6 inch box is 30.5 x 22.9 x 15.2 cm and a 16 x 12 x 8 inch box is 40.6 x 30.5 x 20.3 cm. US shipping boxes are sold in inches, inside dimensions. This chart converts 60 stocked sizes to centimeters, millimeters and liters, and the lookup table turns a metric spec into the smallest stocked box that holds it.
| Box size (in) | Centimeters | Millimeters | Volume |
|---|---|---|---|
| 6 x 6 x 6 | 15.2 x 15.2 x 15.2 cm | 152 x 152 x 152 mm | 3.5 L |
| 8 x 8 x 8 | 20.3 x 20.3 x 20.3 cm | 203 x 203 x 203 mm | 8.4 L |
| 10 x 8 x 6 | 25.4 x 20.3 x 15.2 cm | 254 x 203 x 152 mm | 7.9 L |
| 12 x 9 x 6 | 30.5 x 22.9 x 15.2 cm | 305 x 229 x 152 mm | 10.6 L |
| 12 x 12 x 12 | 30.5 x 30.5 x 30.5 cm | 305 x 305 x 305 mm | 28.3 L |
| 16 x 12 x 8 | 40.6 x 30.5 x 20.3 cm | 406 x 305 x 203 mm | 25.2 L |
| 18 x 18 x 18 | 45.7 x 45.7 x 45.7 cm | 457 x 457 x 457 mm | 95.6 L |
| 24 x 18 x 18 | 61.0 x 45.7 x 45.7 cm | 610 x 457 x 457 mm | 127.4 L |
How to convert box sizes from inches to cm
Corrugated boxes in the US are sold by inside dimensions in inches, written length x width x depth with the largest face first. 1 inch is exactly 2.54 cm, so divide a centimeter spec by 2.54 to get inches, or multiply inches by 2.54 to get centimeters. Because stocked sizes come in whole inches, a metric spec almost never lands exactly on a stocked size; round each dimension up to the next stocked size so the contents still fit.
Worked example: 30 x 23 x 15 cm divided by 2.54 is 11.8 x 9.1 x 5.9 in. Round each up: 12 x 10 x 6 in, which is a stocked size (30.5 x 25.4 x 15.2 cm). If the spec was an outside measurement, subtract about 0.6 cm per dimension first.
Box sizes in cm and mm: 60 standard sizes
Inside dimensions. The last column is the inside volume in liters, useful when a spec sheet quotes capacity rather than dimensions. Sizes link to the stocked box.
| Inches (inside) | Centimeters | Millimeters | Volume |
|---|---|---|---|
| 4 x 4 x 4 in | 10.2 x 10.2 x 10.2 cm | 102 x 102 x 102 mm | 1.0 L |
| 5 x 5 x 5 in | 12.7 x 12.7 x 12.7 cm | 127 x 127 x 127 mm | 2.0 L |
| 6 x 4 x 4 in | 15.2 x 10.2 x 10.2 cm | 152 x 102 x 102 mm | 1.6 L |
| 6 x 6 x 4 in | 15.2 x 15.2 x 10.2 cm | 152 x 152 x 102 mm | 2.4 L |
| 6 x 6 x 6 in | 15.2 x 15.2 x 15.2 cm | 152 x 152 x 152 mm | 3.5 L |
| 7 x 7 x 7 in | 17.8 x 17.8 x 17.8 cm | 178 x 178 x 178 mm | 5.6 L |
| 8 x 6 x 4 in | 20.3 x 15.2 x 10.2 cm | 203 x 152 x 102 mm | 3.1 L |
| 8 x 8 x 4 in | 20.3 x 20.3 x 10.2 cm | 203 x 203 x 102 mm | 4.2 L |
| 8 x 8 x 6 in | 20.3 x 20.3 x 15.2 cm | 203 x 203 x 152 mm | 6.3 L |
| 8 x 8 x 8 in | 20.3 x 20.3 x 20.3 cm | 203 x 203 x 203 mm | 8.4 L |
| 9 x 6 x 4 in | 22.9 x 15.2 x 10.2 cm | 229 x 152 x 102 mm | 3.5 L |
| 9 x 9 x 9 in | 22.9 x 22.9 x 22.9 cm | 229 x 229 x 229 mm | 11.9 L |
| 10 x 6 x 4 in | 25.4 x 15.2 x 10.2 cm | 254 x 152 x 102 mm | 3.9 L |
| 10 x 8 x 6 in | 25.4 x 20.3 x 15.2 cm | 254 x 203 x 152 mm | 7.9 L |
| 10 x 10 x 6 in | 25.4 x 25.4 x 15.2 cm | 254 x 254 x 152 mm | 9.8 L |
| 10 x 10 x 8 in | 25.4 x 25.4 x 20.3 cm | 254 x 254 x 203 mm | 13.1 L |
| 10 x 10 x 10 in | 25.4 x 25.4 x 25.4 cm | 254 x 254 x 254 mm | 16.4 L |
| 11 x 8 x 6 in | 27.9 x 20.3 x 15.2 cm | 279 x 203 x 152 mm | 8.7 L |
| 12 x 6 x 6 in | 30.5 x 15.2 x 15.2 cm | 305 x 152 x 152 mm | 7.1 L |
| 12 x 8 x 6 in | 30.5 x 20.3 x 15.2 cm | 305 x 203 x 152 mm | 9.4 L |
| 12 x 9 x 6 in | 30.5 x 22.9 x 15.2 cm | 305 x 229 x 152 mm | 10.6 L |
| 12 x 9 x 9 in | 30.5 x 22.9 x 22.9 cm | 305 x 229 x 229 mm | 15.9 L |
| 12 x 10 x 6 in | 30.5 x 25.4 x 15.2 cm | 305 x 254 x 152 mm | 11.8 L |
| 12 x 10 x 8 in | 30.5 x 25.4 x 20.3 cm | 305 x 254 x 203 mm | 15.7 L |
| 12 x 12 x 4 in | 30.5 x 30.5 x 10.2 cm | 305 x 305 x 102 mm | 9.4 L |
| 12 x 12 x 6 in | 30.5 x 30.5 x 15.2 cm | 305 x 305 x 152 mm | 14.2 L |
| 12 x 12 x 8 in | 30.5 x 30.5 x 20.3 cm | 305 x 305 x 203 mm | 18.9 L |
| 12 x 12 x 10 in | 30.5 x 30.5 x 25.4 cm | 305 x 305 x 254 mm | 23.6 L |
| 12 x 12 x 12 in | 30.5 x 30.5 x 30.5 cm | 305 x 305 x 305 mm | 28.3 L |
| 13 x 13 x 13 in | 33.0 x 33.0 x 33.0 cm | 330 x 330 x 330 mm | 36.0 L |
| 14 x 10 x 8 in | 35.6 x 25.4 x 20.3 cm | 356 x 254 x 203 mm | 18.4 L |
| 14 x 10 x 10 in | 35.6 x 25.4 x 25.4 cm | 356 x 254 x 254 mm | 22.9 L |
| 14 x 12 x 10 in | 35.6 x 30.5 x 25.4 cm | 356 x 305 x 254 mm | 27.5 L |
| 14 x 14 x 8 in | 35.6 x 35.6 x 20.3 cm | 356 x 356 x 203 mm | 25.7 L |
| 14 x 14 x 14 in | 35.6 x 35.6 x 35.6 cm | 356 x 356 x 356 mm | 45.0 L |
| 15 x 12 x 10 in | 38.1 x 30.5 x 25.4 cm | 381 x 305 x 254 mm | 29.5 L |
| 16 x 10 x 6 in | 40.6 x 25.4 x 15.2 cm | 406 x 254 x 152 mm | 15.7 L |
| 16 x 12 x 6 in | 40.6 x 30.5 x 15.2 cm | 406 x 305 x 152 mm | 18.9 L |
| 16 x 12 x 8 in | 40.6 x 30.5 x 20.3 cm | 406 x 305 x 203 mm | 25.2 L |
| 16 x 12 x 12 in | 40.6 x 30.5 x 30.5 cm | 406 x 305 x 305 mm | 37.8 L |
| 16 x 16 x 8 in | 40.6 x 40.6 x 20.3 cm | 406 x 406 x 203 mm | 33.6 L |
| 16 x 16 x 16 in | 40.6 x 40.6 x 40.6 cm | 406 x 406 x 406 mm | 67.1 L |
| 18 x 12 x 6 in | 45.7 x 30.5 x 15.2 cm | 457 x 305 x 152 mm | 21.2 L |
| 18 x 12 x 12 in | 45.7 x 30.5 x 30.5 cm | 457 x 305 x 305 mm | 42.5 L |
| 18 x 14 x 12 in | 45.7 x 35.6 x 30.5 cm | 457 x 356 x 305 mm | 49.6 L |
| 18 x 18 x 12 in | 45.7 x 45.7 x 30.5 cm | 457 x 457 x 305 mm | 63.7 L |
| 18 x 18 x 18 in | 45.7 x 45.7 x 45.7 cm | 457 x 457 x 457 mm | 95.6 L |
| 20 x 14 x 10 in | 50.8 x 35.6 x 25.4 cm | 508 x 356 x 254 mm | 45.9 L |
| 20 x 16 x 12 in | 50.8 x 40.6 x 30.5 cm | 508 x 406 x 305 mm | 62.9 L |
| 20 x 20 x 12 in | 50.8 x 50.8 x 30.5 cm | 508 x 508 x 305 mm | 78.7 L |
| 20 x 20 x 20 in | 50.8 x 50.8 x 50.8 cm | 508 x 508 x 508 mm | 131.1 L |
| 22 x 22 x 22 in | 55.9 x 55.9 x 55.9 cm | 559 x 559 x 559 mm | 174.5 L |
| 24 x 12 x 12 in | 61.0 x 30.5 x 30.5 cm | 610 x 305 x 305 mm | 56.6 L |
| 24 x 18 x 12 in | 61.0 x 45.7 x 30.5 cm | 610 x 457 x 305 mm | 85.0 L |
| 24 x 18 x 18 in | 61.0 x 45.7 x 45.7 cm | 610 x 457 x 457 mm | 127.4 L |
| 24 x 24 x 12 in | 61.0 x 61.0 x 30.5 cm | 610 x 610 x 305 mm | 113.3 L |
| 24 x 24 x 18 in | 61.0 x 61.0 x 45.7 cm | 610 x 610 x 457 mm | 169.9 L |
| 24 x 24 x 24 in | 61.0 x 61.0 x 61.0 cm | 610 x 610 x 610 mm | 226.5 L |
| 26 x 20 x 14 in | 66.0 x 50.8 x 35.6 cm | 660 x 508 x 356 mm | 119.3 L |
| 30 x 20 x 20 in | 76.2 x 50.8 x 50.8 cm | 762 x 508 x 508 mm | 196.6 L |
| 36 x 24 x 24 in | 91.4 x 61.0 x 61.0 cm | 914 x 610 x 610 mm | 339.8 L |
Box size from a cm or mm spec
Start from the centimeter size you were given and read across to the smallest stocked box that holds it. The match is computed on inside dimensions with every side at least as large as the spec; it ignores orientation labels, so a 20 x 15 x 10 cm spec and a 15 x 20 x 10 cm spec return the same box.
| Spec (cm) | Spec (in) | Nearest stocked box | That box in cm |
|---|---|---|---|
| 10 x 10 x 10 cm | 3.9 x 3.9 x 3.9 in | 4 x 4 x 4 in | 10.2 x 10.2 x 10.2 cm |
| 15 x 10 x 10 cm | 5.9 x 3.9 x 3.9 in | 4 x 4 x 6 in | 10.2 x 10.2 x 15.2 cm |
| 15 x 15 x 10 cm | 5.9 x 5.9 x 3.9 in | 6 x 6 x 4 in | 15.2 x 15.2 x 10.2 cm |
| 20 x 15 x 10 cm | 7.9 x 5.9 x 3.9 in | 8 x 6 x 4 in | 20.3 x 15.2 x 10.2 cm |
| 20 x 20 x 20 cm | 7.9 x 7.9 x 7.9 in | 8 x 8 x 8 in | 20.3 x 20.3 x 20.3 cm |
| 23 x 22 x 31 cm | 9.1 x 8.7 x 12.2 in | 12.25 x 9.25 x 9 in | 31.1 x 23.5 x 22.9 cm |
| 25 x 20 x 15 cm | 9.8 x 7.9 x 5.9 in | 10 x 8 x 6 in | 25.4 x 20.3 x 15.2 cm |
| 30 x 20 x 10 cm | 11.8 x 7.9 x 3.9 in | 12 x 8 x 4 in | 30.5 x 20.3 x 10.2 cm |
| 30 x 20 x 15 cm | 11.8 x 7.9 x 5.9 in | 12 x 8 x 6 in | 30.5 x 20.3 x 15.2 cm |
| 30 x 30 x 30 cm | 11.8 x 11.8 x 11.8 in | 12 x 12 x 12 in | 30.5 x 30.5 x 30.5 cm |
| 35 x 25 x 15 cm | 13.8 x 9.8 x 5.9 in | 14 x 10 x 6 in | 35.6 x 25.4 x 15.2 cm |
| 40 x 30 x 20 cm | 15.7 x 11.8 x 7.9 in | 16 x 12 x 8 in | 40.6 x 30.5 x 20.3 cm |
| 40 x 40 x 40 cm | 15.7 x 15.7 x 15.7 in | 16 x 16 x 16 in | 40.6 x 40.6 x 40.6 cm |
| 45 x 35 x 25 cm | 17.7 x 13.8 x 9.8 in | 18 x 14 x 10 in | 45.7 x 35.6 x 25.4 cm |
| 50 x 40 x 30 cm | 19.7 x 15.7 x 11.8 in | 20 x 16 x 12 in | 50.8 x 40.6 x 30.5 cm |
| 50 x 50 x 50 cm | 19.7 x 19.7 x 19.7 in | 20 x 20 x 20 in | 50.8 x 50.8 x 50.8 cm |
| 60 x 40 x 40 cm | 23.6 x 15.7 x 15.7 in | 16 x 16 x 24 in | 40.6 x 40.6 x 61.0 cm |
| 60 x 60 x 60 cm | 23.6 x 23.6 x 23.6 in | 24 x 24 x 24 in | 61.0 x 61.0 x 61.0 cm |
Inches to cm conversion table
| Inches | cm | mm | cm | Inches | |
|---|---|---|---|---|---|
| 1 | 2.54 | 25.4 | 1 | 0.39 | |
| 2 | 5.08 | 50.8 | 5 | 1.97 | |
| 4 | 10.16 | 101.6 | 10 | 3.94 | |
| 6 | 15.24 | 152.4 | 15 | 5.91 | |
| 8 | 20.32 | 203.2 | 20 | 7.87 | |
| 10 | 25.4 | 254 | 25 | 9.84 | |
| 12 | 30.48 | 304.8 | 30 | 11.81 | |
| 14 | 35.56 | 355.6 | 40 | 15.75 | |
| 16 | 40.64 | 406.4 | 50 | 19.69 | |
| 18 | 45.72 | 457.2 | 60 | 23.62 | |
| 20 | 50.8 | 508 | 80 | 31.50 | |
| 24 | 60.96 | 609.6 | 100 | 39.37 |
Three things that trip up metric conversions
- Inside vs outside. US boxes quote inside; many EU and Asian suppliers quote outside. Single wall board is about 3 mm thick, so an outside spec is roughly 6 mm larger per dimension than the inside space.
- Order of dimensions. US practice is length x width x depth with depth last; some metric specs list height first. Sort the three numbers largest to smallest and compare that way, which is what the lookup table above does.
- Nominal vs actual. A 30 cm side on a box made to inch tooling is usually 12 in (30.5 cm). Treat anything within 5 mm as the same size.
Mailers and poly bags are quoted in inches as well. The poly bag size chart carries a cm column, and the mailer size chart covers bubble and poly mailers. For carrier limits expressed in inches (108 and 130 inches length plus girth, 70 and 150 lb), see package size and weight limits; for billable weight by size, the dimensional weight chart.
Buy these sizes by the case
Every box is listed by its inside size in inches. Each listing shows its box count, and the listed price is for the whole bundle.
Shipping boxes by the bundleHeavy duty and double wall boxesTelescoping boxesGaylord boxesRequest a bulk quote
Orders of one or two items with a product subtotal of $500 or more ship free when the checkout freight rate is $45 or less, or $90 or less on orders of $1,000 or more. Orders of three or more items get the volume discount instead of free shipping. See the shipping policy.
To match an item to a box by its dimensions, use the box size finder.
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Frequently asked questions
What is a 12x12x12 box in cm?
30.5 x 30.5 x 30.5 cm inside (305 mm per side), about 28 liters. Outside it measures roughly 31 x 31 x 31 cm.
How do I convert box sizes from cm to inches?
Divide each dimension by 2.54, then round each result up to the next whole inch that is stocked. 40 x 30 x 20 cm is 15.7 x 11.8 x 7.9 in, which rounds up to 16 x 12 x 8 in.
Are US box dimensions inside or outside?
Inside. The number on a US corrugated box is the usable interior. Add about 6 mm per dimension for the outside size of a single wall box and about 12 mm for double wall.
What box size is 23 x 22 x 31 cm?
9.1 x 8.7 x 12.2 in. Sort largest first (31 x 23 x 22 cm = 12.2 x 9.1 x 8.7 in) and round up: the smallest stocked box that holds it is 12 1/4 x 9 1/4 x 9 in; if you want whole-inch sizing with a little room, 14 x 10 x 10 in.
How many cm is an inch?
2.54 cm exactly, by international definition since 1959. 10 cm is 3.94 in and 100 cm (1 m) is 39.37 in.
What is a standard carton size in cm?
There is no single standard. Popular US cartons are 30.5 x 22.9 x 15.2 cm, which is 12 x 9 x 6 in, 30.5 x 30.5 x 30.5 cm, which is 12 x 12 x 12 in, and 40.6 x 30.5 x 30.5 cm, which is 16 x 12 x 12 in. All three are inside dimensions.