SeeMyQuiltEight-at-a-time half-square triangle calculator
The fastest way to make a lot of identical half-square triangles. Enter the finished size.
Cut squares5 3/4"
- 2 squares of each fabric make 16 units
- Each unit measures 2 1/2" before it is sewn into the block
- Prefer to trim? Cut at 6"
Eight-at-a-time cutting chart
| Finished size | Cut squares | Unit before sewing |
|---|---|---|
| 1" | 3 3/4" | 1 1/2" |
| 1 1/2" | 4 3/4" | 2" |
| 2" | 5 3/4" | 2 1/2" |
| 2 1/2" | 6 3/4" | 3" |
| 3" | 7 3/4" | 3 1/2" |
| 3 1/2" | 8 3/4" | 4" |
| 4" | 9 3/4" | 4 1/2" |
How it is calculated
Place two squares right sides together. Draw both diagonals, then sew 1/4" on each side of both lines. Cut the square in half vertically and horizontally, then cut each quarter on its drawn line. You get eight half-square triangles.
Each quarter is an ordinary two-at-a-time pair, so the large square is twice the finished size plus 7/8", twice over: finished size × 2 + 1 3/4".
Questions
Are the edges on the bias?
No. Like the two-at-a-time method, the outer edges of each unit are on the straight grain, so they do not stretch.
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