How this calculation works
Subtract the combined item bounding volumes from the internal carton volume. Apply an entered loose-to-occupied multiplier and explicit allowance, then round the batch purchase to whole packs.
Loose litres = (carton cm³ − item bounding cm³) / 1,000 × cartons × compression × (1 + allowance)A worked example
A 24 L carton holding two 2 L item boxes has 20 L geometric void. Ten cartons at 1.5 loose litres per void litre with 10% allowance need 330 L, or four 100 L packs.
Good to know
Bounding-volume budget only, not proof items fit or are adequately protected. No drop test, cushion-thickness design or shipping approval. Density and compression are entered material assumptions.
Reference: OpenStax: rectangular prism volume (opens in a new tab) ↗
Internal volume and external shipping dimensions differ
Use usable internal carton dimensions for the void calculation. External dimensions include wall thickness and may be appropriate for a courier weight calculation instead, which is a separate task.
Each item row describes a bounding box and count per carton. Irregular objects may occupy less solid volume than their boxes, but that does not mean all the enclosed space can be filled usefully.
The candle wax and fragrance jar fill calculator adds convert jar volume to blend mass using entered density, distinguish fragrance-on-wax from fragrance-in-blend percentages and account for process loss.
Volume subtraction does not solve three-dimensional packing
A small total item volume is necessary but insufficient for fit. The objects may clash, fail to pass through the opening or leave no required protective clearance even when their sum is below carton capacity.
The calculator rejects a few obvious inconsistencies, but it does not search orientations or prove a packing arrangement. Confirm a physical layout before treating the purchase quantity as an order.
Measure the loose-fill multiplier with the chosen material
Loose purchase volume can settle or compress in use. The multiplier states how many loose litres are needed for each geometric void litre; it is not an automatic protection rating.
Bulk density converts loose litres to a mass estimate. Apply the extra allowance explicitly and round after combining the complete carton batch. Rounding each carton separately would overstate packs when material can be shared.
Use the result with the next measurement
The courier volumetric and billable weight calculator uses external parcel dimensions for transport billing. This dunnage calculation instead uses internal dimensions; copying one measurement into the other can change both estimates.
Bounding-volume budget only, not proof items fit or are adequately protected. No drop test, cushion-thickness design or shipping approval. Density and compression are entered material assumptions.
A few questions, answered
Does this prove the items fit?
No, bounding-volume subtraction is not a packing algorithm.
Which density belongs here?
Loose bulk density of the entered filler, not solid-material density.
Is compression a protective rating?
No, it is an entered volume conversion assumption.