Half Square Triangle Calculator
HST Cutting Size
Calculate the cutting size for half square triangles
in
HST Quilt Layout
Plan an entire HST quilt with block count and fabric needs
in
in
Formula
Cutting size (2-at-a-time) = Finished size + 7/8" | Cutting size (4-at-a-time) = Finished size + 1-1/4" | Square pairs = Total HSTs / Units per method
Frequently Asked Questions
What size do I cut squares for half square triangles?
For the two-at-a-time method, add 7/8 inch to your desired finished size. For example, for 3-inch finished HSTs, cut 3-7/8 inch squares. For the four-at-a-time method, add 1-1/4 inch instead.
How many HSTs can I get from a pair of squares?
The two-at-a-time method yields 2 HSTs per pair. The four-at-a-time method yields 4 per pair, and the eight-at-a-time grid method yields 8 per pair. More units per pair means less waste but slightly more complex construction.
Why do my HSTs come out too small?
Always cut slightly oversized and trim to exact size after sewing. The seam allowance can shift slightly, so cutting 1/8 inch extra and trimming with a square ruler ensures perfect results every time.
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