Box volume calculator
Three measurements in, every volume unit out: cubic inches, cubic feet, cubic centimetres, and litres. Volume is what dimensional weight is built from, so it is worth knowing before you pick a box.
How volume is calculated
- Multiply the three measurements together for cubic inches.
- Divide by 1,728 for cubic feet, since a cubic foot is 12 × 12 × 12 inches.
- For metric, one inch is exactly 2.54 cm, so one cubic inch is 16.387 cubic centimetres. A litre is 1,000 cubic centimetres.
Worked example
A 12 × 12 × 12 inch box.
- 12 × 12 × 12 = 1,728 cubic inches.
- That is exactly 1 cubic foot.
- In metric, 28,317 cubic centimetres, or about 28.3 litres.
Edge cases worth knowing
- Inside and outside volumes differ. The cardboard takes up space. For a box you are shipping, carriers measure the outside.
- Volume does not tell you whether something fits. A 1,000 cu in item does not fit a 1,000 cu in box unless the shapes match. Use the box fit calculator for that.
- One cubic foot is a common threshold. 1,728 cubic inches is where some services begin applying dimensional weight.
- Bulge counts. An overstuffed box measures bigger than the flat carton's stated size.
Common questions
- How many cubic inches are in a cubic foot?
- 1,728. That is 12 × 12 × 12.
- Does a bigger volume always cost more to ship?
- Often, because dimensional weight is calculated from volume. But you are billed on the greater of dimensional and actual weight, so a small dense package can cost more than a large light one.
- Should I measure inside or outside?
- Outside for shipping and carrier limits. Inside for working out what will fit.
- How do I convert to litres?
- Cubic centimetres divided by 1,000. This calculator shows both.