Lid Fit Calculator — Tight-Fitting Box Lids
Calculate lid dimensions and clearance for tight-fitting box lids. Supports overlay, inset, rebated, and sliding styles.
Choose the style that suits your project
Longest dimension of the area
Shortest dimension of the area
Material thickness
How We Calculate This
This calculator determines the correct lid dimensions based on your box size, lid style, and desired clearance.
Lid styles
Overlay: Lid = External dimensions + overhang (typically 3mm per side).
Inset: Lid = Internal dimensions - clearance (0.5-1mm per side).
Rebated: Lid = External dimensions, with a step cut into the underside.
Sliding: Lid slides in grooves cut into the box sides.
Frequently Asked Questions
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Last updated: February 2026
All calculations are estimates. Always verify measurements and material quantities before cutting or purchasing.