Quilt to Size / Half square triangle calculator
Half square triangle calculator
Enter the finished size of your half square triangles. You get the square to cut for each method, rounded up to the next 1/8".
Two at a time
3 7/8"
squares, or 4" and trim. One pair makes 2.
Four at a time
5 1/2"
squares. One pair makes 4.
Eight at a time
7 3/4"
squares. One pair makes 8.
Cut sizes, 1" to 6" finished
| Finished | Unfinished | Two at a time | Four at a time | Eight at a time |
|---|---|---|---|---|
| 1" | 1 1/2" | 1 7/8" | 2 3/4" | 3 3/4" |
| 1 1/2" | 2" | 2 3/8" | 3 3/8" | 4 3/4" |
| 2" | 2 1/2" | 2 7/8" | 4 1/8" | 5 3/4" |
| 2 1/2" | 3" | 3 3/8" | 4 7/8" | 6 3/4" |
| 3" | 3 1/2" | 3 7/8" | 5 1/2" | 7 3/4" |
| 3 1/2" | 4" | 4 3/8" | 6 1/4" | 8 3/4" |
| 4" | 4 1/2" | 4 7/8" | 7" | 9 3/4" |
| 4 1/2" | 5" | 5 3/8" | 7 5/8" | 10 3/4" |
| 5" | 5 1/2" | 5 7/8" | 8 3/8" | 11 3/4" |
| 6" | 6 1/2" | 6 7/8" | 9 3/4" | 13 3/4" |
The three methods
Two at a time: pair two squares cut 7/8" bigger than the finished size, draw a diagonal, sew 1/4" either side, cut on the line. Cut 1" bigger instead if you like to trim to size.
Four at a time: sew all the way around a pair of larger squares, then cut on both diagonals. The bias edges end up on the outside of each unit, so handle them gently.
Eight at a time: draw both diagonals on a pair of squares twice the finished size plus 1 3/4", sew 1/4" either side of both lines, then cut vertically, horizontally and on both diagonals.