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Mortise & Tenon Calculator

Calculate mortise and tenon dimensions using the universal 1/3 rule. Rail, stile, shoulder, cheek and mortise depth — covering IS 883, NDS, Eurocode 5, AS 1720.

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Mortise & Tenon — Calculator

Calculate mortise and tenon dimensions using the universal 1/3 rule. Rail, stile, shoulder, cheek and mortise depth — covering IS 883, NDS, Eurocode 5, AS 1720.

Joint Type & Application
Unit System
Joint Type
Application
Member Dimensions
Rail Width (mortised member)
mm
Rail Thickness
mm
Stile Thickness (tenon member)
mm
Rail Span (reference)
mm
Load Category

⚙ Mortise & Tenon Calculator

The world's oldest wood joint — found in ancient Egyptian furniture (3000 BC), traditional Indian carpentry, European timber framing and Japanese temple construction. The tenon (projecting tongue) fits the mortise (rectangular hole), creating a strong connection resisting racking, tension and bending.

Where Used?

Door & Window FramesChair & Table LegsPost & BeamCabinet FramesStaircaseTraditional Indian Furniture

Formulas (1/3 Rule — IS 883, NDS, Eurocode 5, AS 1720)

Tenon thickness = Rail thickness / 3Tenon width = Rail width − 2 × shoulder_allowanceTenon length = 4.5 × tenon_thickness (max = 80% of stile thickness)Mortise depth = Tenon length + 2mm clearanceCheek = (Rail thickness − Tenon thickness) / 2

FAQ

What is the 1/3 rule?
Tenon thickness = 1/3 of rail thickness. This leaves 1/3 for the mortise cavity and 1/3 cheek each side — balancing joint strength with structural integrity of the mortised piece. Used globally across IS 883, NDS 2018, Eurocode 5 and AS 1720.
Used in Indian carpentry?
Yes — called "chool aur khana" in some regions. Foundation of traditional Indian furniture in Rajasthan, Gujarat and South India. Modern craftsmen use identical 1/3 rule to international standards.
ResourcesView the formulasFormula Library