Calculation method
This calculator uses the following planning method:
Mailer width = product width + thickness + 2 × clearance; mailer length = product length + thickness + clearance + flap
Worked example
A 10 × 8 × 2 in item with 0.5 in clearance and a 2 in flap needs about 11 × 14.5 in of usable internal mailer space.
How to interpret the result
Round up to a stocked mailer size and confirm the published usable dimensions below the adhesive seal.
Assumptions and limitations
The estimate assumes a flexible mailer and a regular product. Rigid corners, compression, seams, and gussets change fit.
Estimate only. Verify the packed result with actual materials and the current requirements of your supplier, marketplace, or carrier.