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Quilting Dictionary

Half-Square Triangle (HST)

Piecing
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A pieced unit made from two right triangles sewn together along their diagonal to form a square — one of the most common building blocks in quilting.

Half-Square Triangle (HST) Geometry

Two right-angle triangles joined along their hypotenuse diagonal to form a clean square unit.

1. Diagonal Seam Lines
2. Pressed Square UnitStraight Grain

Also see

QuiltingBlock

More Piecing terms

Keep exploring the glossary.

AppliquéSewing a fabric shape onto a background fabric to create a design, either by hand or machine, as opposed to piecing shapes together.Chain PiecingFeeding pieces through the sewing machine one after another without cutting the thread between them, to save time and thread.English Paper Piecing (EPP)Hand-piecing fabric around paper templates (often hexagons) and whipstitching the folded edges together.Foundation Paper PiecingSewing fabric directly onto a printed paper pattern for precise, intricate piecing, then removing the paper afterward.Half-Rectangle Triangle (HRT)Like a half-square triangle, but cut from a rectangle instead of a square — creates elongated, angled triangle units.Nesting SeamsPressing opposing seam allowances in opposite directions so they interlock and lie flat where two seams meet.

Put it into practice

Block LibraryBrowse classic pieced blocks and their history.Pattern MakerDrag blocks onto a grid to design your own quilt top.Yardage CalculatorWork out exactly how much fabric your quilt needs.
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