setting triangles

when piecing a quilt that has blocks set on point, you want to cut the setting and corner triangles so the edge of the quilt top is on the straight of grain. this is important to keep the edge from stretching when you go to sew on your borders.

side triangles are the teal along the edges and the corner triangles are orange.

here's a chart of some of the most 'common' block sizes and the square size to cut for setting triangles and corner triangles. this chart will give you exact on point corners- the block's corner will be exactly on the seam. if you want your block corner to float- add an 1/2" to 1" to the square size listed. clear as mud, right?

for side setting triangles, you will cut the square across both diagonals.

for the corner triangles you cut 2 squares once across the diagonal (you'll only need 2 squares because a quilt only has four corners).

i recommend spraying the fabric with some sizing, best press, or starch before cutting to help stabilize the bias edges.

for those that are interested, here is the math formula for figuring out the square size. i round up to the nearest 1/8 inch.

for the side setting triangles:
multiply finished block by 1.414 and add 1.25
for the corner triangles:divide finished block by 1.414 and add .875

and i use to H.A.T.E. math....


  1. Thanks for making a chart that is so easy to understand.

  2. Thanks so much for the chart and formulas! I had no clue how to calculate corner triangles and I love quilt squares on point.

  3. Shannon, I can't believe I stumbled on this just as I was about to try to work this out (Mumbling now, having just unpicked the borders of my next quilt and tossed the triangles I cut cos they,were waving at me) and as I am a new long armer I could do with making loading as simple as possible so I can concentrate on the rest. I really should have known better. Thank you, Thank you, Thank you for helping stupid girl out this morning.


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