How the Packaging Calculator Works
Enter your product dimensions (length, width and height), select your packaging type, set the clearance around each side, and specify the board thickness. The calculator uses these inputs to estimate the recommended internal box size and the resulting external dimensions.
The formulas are straightforward: for each axis, the internal dimension equals the product dimension plus twice the clearance (one clearance value applied to each side). The external dimension then adds twice the board thickness to account for both walls of the box.
Internal vs External Box Dimensions
Internal dimensions describe the usable space inside the box — the area available for your product, inserts and any protective materials. When specifying packaging requirements to a manufacturer, internal dimensions are typically the primary reference.
External dimensions include the material thickness of the box walls. These matter for shipping calculations, carton packing and pallet planning, since carriers and freight forwarders work with the outer envelope of the package.
How Much Clearance Should I Add?
Clearance depends on the product, insert, protection level and packaging structure. A snug rigid box with a custom insert may need very little clearance, while a product without an insert may need more space to prevent movement.
Fragile or irregular products may require additional space or a custom insert. As a general starting point, 2–5 mm per side is common for products with some form of insert protection, but the right clearance is always specific to the product and packaging design.
Example Calculation
Product: 123 × 23 × 42 mm
Clearance: 3 mm per side
Board thickness: 2 mm
Recommended Internal Box Size: 129 × 29 × 48 mm
Estimated External Box Size: 133 × 33 × 52 mm
Limitations
This calculator provides estimated dimensions for preliminary packaging planning. It is not a production dieline generator or a final engineering specification. Actual box dimensions may vary based on box structure type, material properties, manufacturing tolerances, insert design and finishing methods.
For production-ready packaging, work with a packaging manufacturer to develop precise structural specifications, physical samples and production-grade dielines.
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