Define the purchasing question
Internal dimensions control product fit. External dimensions control freight envelope and pallet placement. Substituting one for the other changes the answer.
Use internal dimensions for item fit and external dimensions for CBM, dimensional weight and pallet layouts. Keep both in the purchasing specification.
Collect measurements that match the calculation
Start with a measured product envelope including allowed orientation. Add specified clearance and cushioning on both faces. Obtain final outside dimensions from the converter rather than treating board thickness as a complete style allowance.
Add allowances on both opposing faces. Internal fit dimensions and external shipping dimensions remain separate. Use final converter-confirmed external measurements before requesting freight.
- Product length (mm)
- Product width (mm)
- Product height (mm)
- Clearance per side (mm)
- Cushioning per side (mm)
- Board thickness (mm)
Work through an illustrative case
Internal side = Product side + 2 × (Clearance + Cushioning); External side = Internal side + 2 × Board
A 200 mm product with 5 mm clearance and 10 mm cushioning per side needs 230 mm internal length; 4 mm board gives an estimated 238 mm external length.
Replace these illustrative inputs with measured data or a quotation for the same scope. Change one assumption at a time so that a difference can be traced to a dimension, quantity, charge or process change.
Avoid the expensive comparison error
Flat blank dimensions, internal size and outside size are three different measurements. Real folds, tolerances and closures can exceed a simple wall-thickness estimate.
- Rectangular envelope only; folds and manufacturing tolerances need confirmation.
- Cushioning thickness is entered, not a protection recommendation.
Common questions
What should I verify before using this result?
Start with a measured product envelope including allowed orientation. Add specified clearance and cushioning on both faces. Obtain final outside dimensions from the converter rather than treating board thickness as a complete style allowance.
Does this calculation approve the packaging?
No. It estimates only the stated quantity, conversion or cost boundary. Technical performance and any required test or supplier approval remain separate.