Cathedral window calculator

This calculator can tell you how big you have to cut the squares for your cathedral window project (pillow, quilt…). The allowance (for ironing with the template) is already included in the calculation. You don’t have to add anything to the calculated sizes.

And that’s how it works:

  • Choose the desired width of the finished pillow / quilt.
  • Enter the number of squares per row.
  • Click “inches” or “cm”.
  • Hit “Calculate”.
Cathedral Window Calculator

Cathedral Window Calculator

inches / cm

inch cm

inches / cm

inches / cm



My calculations are based on the Youtube-Tutorial by Shabby Fabrics. They include an extra 1 inch / 3 cm for ironing with the template. As shown in the video you cut your template 1 inch / 3 cm smaller than your square on each side.