Mortise and Tenon Size Calculator
Standard Mortise and Tenon
Calculate tenon dimensions from stock size
Formula
Tenon Thickness = Stock Thickness / 3 | Tenon Length = Stock Width x 0.75 | Shoulder = (Stock - Tenon) / 2
Frequently Asked Questions
What is the rule of thirds for tenons?
The traditional rule is to make the tenon thickness one-third of the stock thickness, leaving equal-sized shoulders on each side for a balanced, strong joint.
How long should a tenon be?
A tenon should be about 3/4 of the width of the stock it enters. This provides good glue surface while leaving enough material around the mortise.
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