Use this workshop calculation to turn measured dimensions and the selected construction convention into a cut, spacing, fit, or material-planning value.

Board thickness (mm)

Board thickness in millimeters.

Compute the lap thickness and cut depth that halve a cross-lapped board. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Lap thickness (mm)

Remaining material thickness of each lapped board.

Cut depth (mm)

Depth of material removed from each board face.

• Nominal dimensions, kerf, moisture movement, hardware clearances, wall squareness, and manufacturer instructions can change the required shop dimension. Measure the actual assembly and test critical joints on scrap before cutting finished material.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Complement the calculated dimension with a physical story stick, dry fit, or full-size layout. Follow the hardware, coating, adhesive, or machine manufacturer's limits where they differ from a rule of thumb.

• Ueberblattung Tiefe Half

  Cut depth for a centered half-lap joint in a board of uniform thickness.

• Box Joint Depth

  Size box-joint fingers from mating board thickness plus deliberate protrusion before flushing.

• Dado Depth

  Calculate target dado depth from board thickness and an explicitly chosen fraction of that thickness.