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

Inside Width Mm (mm)

Required number input.

Muntin Count

Required integer input.

Muntin Width Mm (mm)

Required number input.

Equal clear opening width between identical muntins across a frame, including both end gaps. 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]

Clear Gap Mm (mm)

The resulting clear gap mm 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.

• 4-Inch Baluster Spacing

  Count equal-width balusters and calculate equal clear gaps, including both end gaps, so none exceeds a four-inch maximum.

• Fence Picket Spacing

  Calculate equal clear gaps between fence posts, pickets, and both ends from opening width and uniform picket width.

• Trellis Lath Spacing

  Equal clear gap including both end gaps when equal-width trellis laths fill a known inside span.