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Half square triangle calculator
Cut sizes for 2, 4 and 8 at a time HSTs.
In short
For 2 at a time half square triangles, cut squares the finished size plus 7/8 in (plus 2.6 cm). A 3 in finished HST starts from 3 7/8 in squares. For 8 at a time, cut squares twice that size: 7 3/4 in for 3 in finished units.
in
HST
Method
Cut squares
Pairs of squares
Makes
Trimmed unit before sewing
How to use it
- Enter the finished size of each HST.
- Pick a method. 2 at a time is the most accurate, 8 at a time is the fastest.
- Cut one light and one dark square for each pair, then sew and cut.
Pip's tips
- 4 at a time units have bias edges. A little starch keeps them crisp.
- Adding 1/4 to 1/2 in (0.5 to 1 cm) and trimming down gives perfectly sharp points.
- Press toward the darker fabric, or open for flatter blocks.
Sources: Every number follows the SewNQuilt quilting and sewing standards, built from published industry references. Imperial and metric are calculated natively, never converted piece by piece.
Keep this with you
Save every result to a project, add fabric to your shopping list and work offline in the SewNQuilt app.
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