Separate exterior format from usable interior
Record box and board dimensions in millimetres, but use interior dimensions and actual component thickness for pack-out decisions. A named square-box format does not establish its wall thickness, insert volume, folded-board clearance, or lid tolerance.
How to apply it
A 220 mm folded board may fit a 250 mm exterior box in plan view while still conflicting with a deck well, rulebook, or insert. Begin with component stack measurements, add planned clearance, and verify the result with a physical pack-out.
Questions and decisions
Board folds, score width, chipboard thickness, paper wrap, and packing method vary by supplier. Ask for an approved dieline or structural drawing before committing to artwork or an insert.
Next step
Use the linked tools with your project’s documented inputs, retain the source or quote date beside the scenario, and update the decision when the specification changes.