SeeMyQuiltSetting triangles calculator (on point)
For blocks set on point. Enter the block size and layout to get the squares to cut for the side and corner triangles.
Side triangles3 squares 18 1/4"
- Cut twice on the diagonal for 10 side triangles
- Corners: 2 squares 9 3/8", cut once on the diagonal
- 18 blocks in total
Setting triangle chart
| Finished block | Side triangles: cut squares | Corner triangles: cut squares |
|---|---|---|
| 6" | 9 3/4" | 5 1/8" |
| 8" | 12 5/8" | 6 5/8" |
| 9" | 14" | 7 1/4" |
| 10" | 15 1/2" | 8" |
| 12" | 18 1/4" | 9 3/8" |
| 14" | 21 1/8" | 10 7/8" |
| 16" | 24" | 12 1/4" |
How it is calculated
Side triangles are cut from large squares cut twice on the diagonal, so the long edge, which ends up on the outside of the quilt, is on the straight grain. The square is the block size times 1.414 plus 1 1/4".
Corner triangles are cut from smaller squares cut once on the diagonal: the block size divided by 1.414 plus 7/8".
Many quilters cut these squares an inch larger and trim the quilt after the rows are joined.
Questions
Why are the side triangles cut differently from the corners?
To keep the straight grain on the outer edge of the quilt. A bias edge there would stretch and ripple.
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