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

Groove width (mm)

Required number input.

Total fit clearance (mm)

Required number input.

Find tongue thickness from mating groove width after subtracting an explicit total fit clearance. 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]

Tongue thickness (mm)

The resulting tongue thickness returned as a number.

• 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.

• Inlay Strip Width

  Set inlay-strip cut width from a measured groove width after subtracting a chosen total fit clearance.

• Dado Width

  Allow a dado to fit a measured panel thickness with explicit total width clearance.

• Feder Nut Masse 1 3 Regel

  One-third-rule tongue thickness from stock thickness and groove width after a user-selected fitting clearance.