When you position quilt blocks on point (also called a diagonal set), you need to fill in the outer edges of the quilt with triangle-shaped cuts of fabric. Triangles along the side of the quilt are called side setting triangles. Corner setting triangles fit the corners of the quilt.
Blocks set on point
To calculate the size to cut the side setting triangles:
- Multiply the finished size of your block by 1.414
- Add 1 1/4″ to that number
- Cut a square equal to the sum
- Cut the square twice, corner to corner
Example for a 6″ block:
6″ x 1.414 = 8.484 (round up to 8 1/2″)
8 1/2″ + 1 1/4″ = 9 3/4″
Cut a square 9 3/4″ and cut it twice, corner to corner.
Use quarter square triangles for side setting triangles.
To calculate the size to cut corner setting triangles:
- Divide the finished size of your block by 1.414
- Add 7/8″ to that number.
- Cut a square equal to the sum
- Cut the square once, corner to corner
Example for a 6″ block:
6″ ÷ 1.414 = 4.24″ (round up to 4 1/4″)
4 1/4″ + 7/8″ = 5 1/8″
Cut a square 5 1/8″ and cut it once, corner to corner.
Use half square triangles for corner setting triangles.
Happy Quilting,
The Tech Editors
This tutorial is an excerpt from Sharyn Craig‘s portion of the Piecing Tips and Tricks Tool.
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9 Comments
Thanks for the handy chart, very useful.
It’s much simpler and quicker (avoids the math) to measure the on-point block on the diagonal from point to point. Add 1/2 inch to that measurement and that is the size of the block for your setting triangles.
Forgot to say that the four corner triangles are cut from a rectangular block that is the measurement of the diagonal of the on-point block long by 1/2 that measurement wide. Cut that in half and then cut those two blocks on the diagonal.
There’s a typo in the chart: the corner-triangle formula at the bottom of the chart says to divide by 1.141. It should be 1.414 (the square root of two). A spot-check of the chart itself shows that it uses the correct formula.
Thanks for the chart, and thanks to calicoedcat for the alternate method.
Thanks to CT Publishing & Calicoed Cat. I needed this right now! Perfect!
by chance can anyone tell me how to set these seams up correctly so I do not get puckers on the quilt top at the point where you stitch the triangle tip? And would the same technique be used when sewing the corners? Any assistance would soooooo be greatly appreciated.
Thank You all so very much and “Happy Stitching”
Hi JoAnne,
I would put together my quilt rows on the diagonal and then stitch the individual rows together. That way, there are no y-seams to stitch at the corners of the setting triangles.
THANKS FOR THIS INFO. have always wanted to know this
Wonderful chart. Easy to understand. I will be using it this month. Thank you for publishing this info.