The Equilateral Triangle Quilt Calculator is designed to help quilters understand how large their pieced quilt top made from equilateral triangles (60° triangles) will become. Instructions and graphics explaining the inputs and outputs are located below the calculator.

The calculator is an Excel file that you will download to use. To download, click on the image below and save the file to your computer.

Instructions

• Blue text / blue cells are required input
  • Click on desired input cell and type in numeric value. Clicking away or pressing Enter will update the output fields.
• Red text is output
  • If you accidentally type over the red numbers, a message will appear notifying you that those cells are protected and the spreadsheet will update back to the correct formula and output.

Input

• The Height of Strip input is the dimension of your equilateral (60°) triangles from the top point to the base prior to piecing. This dimension is typically noted as 5″ x WOF (width of fabric) in cutting instructions (in this case, the input would be 5).

• An example of a 16 across by 12 down quilt top is shown above. If you are using the tool to determine the number of triangles to cut for your quilt top, multiply the number across by the number down (16 x 12) to find the total number of triangles needed for your quilt top (192 in this example).
• Number of Fabrics in Quilt
• Width of Fabric (WOF)

Output

• When piecing equilateral triangle quilt tops, you may choose to piece in half triangles at the beginning and end of each row. If you choose to piece in half triangles, the size of your pieced quilt top is noted in the “Edge Finishing: Piece Half Triangles” output section.

• You may also choose to trim the quilt back to the points or leave the edges non-square. If you choose one of these piecing options, the size of your pieced quilt top is noted in the “Edge Finishing: Trim” output section.
• The output will also tell you basic cutting instructions for each of the fabrics in your quilt assuming an even color/fabric distribution in the quilt. You will get an estimate of the yardage to purchase. Cut the indicated “Number of WOF per fabric” WOF strips using first input you selected as the height of strip. In the example image, that means cutting (7) 6″ x WOF strips for each fabric.

Questions? Comments? Concerns? Requests?

Please leave a comment or email me at yvonne (at) quiltingjetgirl (dot) com. Especially let me know if you have requests for similar tools!