Start with the product envelope
Measure maximum dimensions with orientation and units. Include protrusions and any product-level protectors. Keep the source of the measurement visible, especially if it is an estimate.
Discuss internal allowances
Ask the supplier to design the required support and protection. The notebook calculator adds an illustrative geometric gap; it does not select cushioning or account for structural design. Record the final inside specification separately.
Get the final outside size
Ask for assembled outside dimensions after construction and closure are defined. Use those confirmed dimensions for the transport conversation. Avoid converting inside space directly into a quoted freight footprint.
Technical context: PCA · packaging to contain products ↗. This note prepares a specification conversation. Confirm the actual design and shipping requirements with the responsible supplier and carrier.