Printable half square triangle chart
One half square triangle chart for every finished size a quilter plans: cut two starting squares ⅞″ bigger than the finished unit, sew, and subcut on the diagonal. The table below works that rule — and the four- and eight-at-a-time variants — through 13 finished sizes, every value computed by Quilt Block Atlas, ready to print.
The chart — 1″ to 8″ finished
The three method columns are the size to CUT. Finished size is the unit after it is sewn in; Trim to is what the sewn unit should measure before its outer seams — the finished size plus ½″. Two- and eight-at-a-time starting squares are exact. Four-at-a-time is the rounded-and-trimmed method: its starting square is rounded up to the next ⅛″, and each unit is trimmed to the Trim to column.
Scroll sideways to see every method.
| Finished size | Trim to | Two at a time | Four at a time | Eight at a time |
|---|---|---|---|---|
| 1″ | 1½″ | 1⅞″ | 2⅝″ | 3¾″ |
| 1½″ | 2″ | 2⅜″ | 3⅜″ | 4¾″ |
| 2″ | 2½″ | 2⅞″ | 4⅛″ | 5¾″ |
| 2½″ | 3″ | 3⅜″ | 4¾″ | 6¾″ |
| 3″ | 3½″ | 3⅞″ | 5½″ | 7¾″ |
| 3½″ | 4″ | 4⅜″ | 6¼″ | 8¾″ |
| 4″ | 4½″ | 4⅞″ | 6⅞″ | 9¾″ |
| 4½″ | 5″ | 5⅜″ | 7⅝″ | 10¾″ |
| 5″ | 5½″ | 5⅞″ | 8⅜″ | 11¾″ |
| 5½″ | 6″ | 6⅜″ | 9″ | 12¾″ |
| 6″ | 6½″ | 6⅞″ | 9¾″ | 13¾″ |
| 7″ | 7½″ | 7⅞″ | 11⅛″ | 15¾″ |
| 8″ | 8½″ | 8⅞″ | 12⅝″ | 17¾″ |
Which column to use
Scroll sideways to inspect every label.
Two at a time: cut 2 squares from the Two at a time column beside your finished size, sew a seam each side of the drawn diagonal, subcut on it once, and get 2 exact units. This starting square is exact; the Eight at a time starting square is exact too.
Four at a time: cut 2 squares, sew around the perimeter, cut both diagonals, and get 4 units with bias outer edges. The starting square is rounded up, so every unit is trimmed to the Trim to column — plan on the extra pass.
Eight at a time: cut 2 larger squares, sew a seam each side of both drawn diagonals, cut on both diagonals and twice through the middle, and get 8 matching units from an exact starting square — the batch method for a block that repeats one unit. For any size this chart does not print, the half square triangle calculator takes every ⅛″-multiple finished size.
Blocks these squares build
11 blocks in this library are pieced from half square triangles, each with its own chart at any size.
- Bear's Paw
- Broken Dishes
- Card Trick
- Churn Dash
- Friendship Star
- Heart
- Jacob's Ladder
- Maple Leaf
- Pinwheel
- Shoofly
- Sister's Choice
Print this chart at 100%
Press Ctrl+P (⌘P on a Mac) and choose "Actual size" or 100% — never "Fit to page". Then measure this square: it must be exactly 1″. If it is not, the whole sheet is scaled and every number on it is wrong — printing quilt patterns at 100% walks through the settings.
Related pages
- Half square triangle blocks Browse every HST-bearing block and its terminology.
- Half square triangle calculator Compare two-, four-, and eight-at-a-time HST starting squares.
- Printing quilt patterns at 100% Calibrate the one-inch square before cutting.
Common questions
Why add ⅞ inch and not just ½ inch?
½″ covers the seam allowance on the edges, and the remaining ⅜″ survives the diagonal cut — a diagonal seam consumes more than a straight one. Cut only ½″ bigger and every unit finishes small, which is the most common HST complaint there is.
Can I cut the squares bigger and trim them down?
Yes — cutting oversize and trimming down is widely taught, and the published amounts differ by source; how to square up a quilt block carries the attributed range. The trim target is the Trim to column: a 3″ finished unit is trimmed at 3½″, never at 3″. Oversizing costs fabric and a trimming pass; the chart's exact numbers cost accuracy at the seam instead. Both work — pick one and be consistent.
How do I print this chart at actual size?
"Actual size" or 100%, never "Fit to page" — then measure the calibration square above with a real ruler before cutting anything. The setting is what you asked for; the square is what you got.
My finished size is not on the chart — where do I get it?
The half square triangle calculator computes the same three methods at any ⅛″-multiple finished size, and every block page's own chart recomputes as you type.