Mortise and Tenon Calculator
Professional woodworking joint calculator for traditional mortise and tenon joinery. Calculate precise dimensions, tolerances, and joint strength with safety guidelines for perfect fits.
⚠️ WOODWORKING SAFETY NOTICE
Always wear appropriate safety equipment when cutting mortises and tenons. Use sharp, properly maintained tools. Test joints on scrap wood first. Ensure proper grain orientation for maximum joint strength. Follow manufacturer's guidelines for power tools and hand tools.
Joint Specifications
Stock Dimensions
Joint Configuration
Wood Species & Tolerances
Joint Calculations
Enter your stock dimensions and joint specifications, then click "Calculate Joint Dimensions" to see your mortise and tenon measurements.
Mortise Sizing Rules
Mortise width should be 1/3 of stock thickness. Mortise length typically equals tenon width minus 1/16" for clearance. Depth should exceed tenon length by 1/8".
Tenon Proportions
Tenon thickness should be 1/3 of stock thickness. Width typically 2/3 of stock width. Length depends on joint type and structural requirements.
Joint Tolerances
Standard fit: 0.005"-0.010" clearance. Tight fit for structural joints. Loose fit for seasonal wood movement. Test fit on scrap wood first.
Grain Orientation
Align grain direction for maximum strength. Avoid short grain in tenon cheeks. Consider seasonal wood movement in joint design and tolerances.
Cutting Techniques
Use sharp chisels and saws. Cut mortise first, then fit tenon. Multiple light passes for clean cuts. Square up mortise walls with chisels.
Assembly Tips
Dry fit before gluing. Use appropriate clamps. Apply glue to mortise walls, not tenon. Allow proper cure time before stress loading.
How Mortise and Tenon Joints Work
Traditional Joinery Principles
Mortise and tenon joints are among the strongest woodworking joints, relying on precise mechanical fit and large glue surface area. The tenon (male part) fits snugly into the mortise (female part), creating a joint that resists both tension and compression forces.
Strength Calculation
Joint strength depends on glue surface area, wood species, grain orientation, and fit tolerance. Our calculator considers these factors to recommend optimal dimensions for maximum strength while maintaining workability.
Tolerance Engineering
Proper tolerances ensure strong joints without splitting. Too tight causes assembly problems and potential cracking. Too loose reduces glue contact and joint strength. Our calculator provides species-specific recommendations.
Frequently Asked Questions
The traditional rule is that mortise width should be 1/3 of the stock thickness, and tenon thickness should match the mortise width. This provides optimal strength while maintaining sufficient material around the mortise to prevent splitting.
Allow 0.010"-0.015" clearance for hardwoods and 0.015"-0.020" for softwoods in humid climates. Consider wood species movement characteristics and final environment conditions. Quarter-sawn lumber moves less than plain-sawn.
Always cut the mortise first, then fit the tenon to match. Mortises are harder to adjust than tenons. Use the mortise as your reference and carefully pare the tenon for a perfect fit.
Essential tools include: sharp chisels (1/4", 3/8", 1/2"), mortise gauge, tenon saw or dovetail saw, drill bits for waste removal, and a mallet. Power tools like mortising machines and table saws can speed production.
Use sharp tools, score the mortise outline first, remove waste gradually, and support the work piece properly. Clamp a backing board to prevent tear-out. For deep mortises, drill out most waste before chiseling to final dimensions.
Blind mortises don't go completely through the stock, hiding the joint. Through mortises go all the way through and are often wedged for extra strength. Blind joints look cleaner but through joints can be stronger and easier to cut accurately.