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

Screw Diameter Millimeters (mm)

Required number input.

Rule-of-thumb pilot diameter equal to 70% of a wood screw's outside diameter; adjust for screw and timber manufacturer guidance. 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]

Pilot Diameter Millimeters (mm)

The resulting pilot diameter millimeters 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.

• Screw Pilot Hole Calculator

  Compute pilot hole diameter and depth for a wood screw with 6 mm tip clearance.

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  Rule-of-thumb wooden dowel length equal to five times dowel diameter; verify actual embedment and joint design.

• Screw Pull-Out Estimate

  Estimate screw pull-out resistance in kilograms from core diameter, penetration depth, and wood group.