How far from the edge should I place box hinges?

Typically 1.5 times the hinge length from each end, or about 10% of the box length - whichever is greater. This prevents the hinge mortise from weakening the corner joints and looks well-proportioned.

How many hinges does a box need?

Small boxes (under 250mm) need 2 hinges. Medium boxes (250-500mm) use 2-3 hinges. Large boxes and chests (over 500mm) should have 3 or more. A long piano hinge is another option for large lids.

How deep should a hinge mortise be?

The gain (mortise) is cut exactly to the thickness of the hinge leaf, typically 1-2mm, so the leaf sits flush with the wood surface when closed. Use a sharp chisel or a router with a straight bit for accurate depth.

How wide should I cut the hinge gain?

The gain width equals the hinge leaf width, which is half the open width (the dimension across both leaves with the hinge laid flat). Read this off your hinge data sheet — it is set by the hinge itself, not by the hinge length. A 32mm box butt hinge can have a 21mm open width (about a 10.5mm leaf) or 27mm (about a 13.5mm leaf) depending on the model.

WoodCalcs

Hinge Placement Calculator — Box Lid Hinges

Determine hinge positions and mortise dimensions for box lids. Get evenly spaced hinges every time.

Box Length (back edge)

Length of the back (hinge) edge where the lid meets the base.

Hinge SizeHinge length along the knuckle/pin — box butt hinges are sold by this length.

Number of Hinges

Material Thickness

Thickness of the box wall at the hinge edge — the gain must stay shallower than this.

How We Calculate This

This calculator determines the optimal placement for box hinges based on the box length, hinge size, and number of hinges.

Placement rules

Hinges are positioned with equal insets from each end. For multiple hinges, the remaining span is divided equally. The inset distance is the greater of 1.5x hinge length or 10% of the box length.

Gain (mortise) dimensions

The gain runs the full hinge length along the back edge and is cut to the depth of the leaf thickness so the hinge sits flush. Its width equals the hinge leaf width — half of the open width measured across both leaves. Open width is a fixed property of the hinge and does not scale with its length, so it is taken from a per-size default (or your own data-sheet figure in Advanced Options) rather than calculated from the length.

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.