Mitre Box Calculator — Mitre Joint Box Dimensions

Mitre joints hide the end grain at corners, giving a clean, elegant appearance. The grain appears to wrap around the corners. They are ideal for decorative boxes, especially when the wood has attractive grain patterns.

Mitres can be reinforced with splines (thin strips of wood across the joint), biscuits, dowels, or simply with glue on well-fitted joints. For small boxes, PVA glue alone on accurately cut mitres is often sufficient.

Use a mitre saw set to exactly 45 degrees, a table saw with a mitre gauge, or a shooting board with a 45-degree fence. Test the angle by joining four offcuts - they should form a perfect 90-degree corner.