How this calculator works
A solid rectangular box has volume length times width times height. Multiply by identical-piece count and uniform density to obtain total mass. Reverse dimensions use either total volume or total mass with density, and the other two dimensions. The result assumes the whole outside envelope is solid; packaging, hollow boxes, cavities and mixed materials need separate component volumes. Weight in this page name means mass, rather than gravitational force.
Formula
Vtotal = length x width x height x quantity; mass = Vtotal x density; density = mass / Vtotal; length = Vtotal / (width x height x quantity), with analogous rearrangements for width and height.
Worked example
One 2 x 3 x 4 m solid box has volume 24 m3. At 100 kg/m3 it has mass 2400 kg. Using that mass and density with length 2 m and width 3 m recovers the 4 m height.
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Frequently asked questions
Does this calculate shipping dimensional weight?
No. Shipping carriers use a pricing divisor. This calculator uses physical material density to estimate actual solid mass.
Can I enter pounds per cubic foot?
Yes. The density selector converts pounds per cubic foot to the base density while dimensions can use metric or imperial units.
Does a box need a uniform material?
Yes for a single density. For a composite assembly, calculate each component mass and add the results.