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

Joint width (mm)

Required number input.

Tail count

Required integer input.

Each end pin width (mm)

Required number input.

Interior pin width (mm)

Required number input.

Lay out equal dovetail tails between two end pins and equal interior pins; report tail width and center pitch. 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]

Equal tail width (mm)

The resulting equal tail width returned as a number.

Tail center pitch (mm)

The resulting tail center pitch 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.

• Dovetail Pin Width

  Solve equal interior pin width from joint width, two end pins, tail count, and equal tail width.

• Dovetail Tail Count

  Count complete dovetail tails that fit an available joint width after reserving equal end pins and interior pin widths.

• Biscuit Spacing

  Equal center-to-center spacing for a chosen number of biscuits placed between equal end offsets along a joint.