FullCalculator

Woodworking Joint Dimension Calculator

Mortise & Tenon

Calculate mortise and tenon dimensions

Dovetail Joint

Calculate dovetail pin and tail dimensions

Box / Finger Joint

Calculate box joint dimensions and spacing

Formula

Tenon Thickness = Stock Thickness / 3 | Tenon Length = Stock Thickness × 2 | Dovetail Angle = arctan(1/ratio)

Frequently Asked Questions

What size should a mortise and tenon be?
The standard rule is that the tenon thickness should be 1/3 of the stock thickness. The tenon length should be 2-3 times the stock thickness. The mortise width matches the tenon thickness and should be cut to the nearest chisel size. Leave 1/8" shoulders on each face for a clean look.
What is the correct dovetail angle?
For hardwoods, use a 1:8 ratio (about 7 degrees). For softwoods, use a 1:6 ratio (about 9.5 degrees). A 1:7 ratio works well as a general-purpose angle for mixed wood projects. The steeper angle (1:6) provides more mechanical strength in softer woods.

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