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Seam lines shown. The colors show which fabric goes where. You pick the fabrics on the Design Wall.

Half-square triangles

Half Square Triangle

A 6 inch finished block, pieced from 2 fabrics. The cut list below has every size.

Cut list

What to cut for one 6 inch finished block. A quarter inch seam allowance is already in every size.

Feature

1 square
6⅞"Cut once on the diagonal, layered with the background fabric. Each square makes 2 triangles. This block uses 1.

Background

1 square
6⅞"Cut once on the diagonal, layered with the feature fabric. Each square makes 2 triangles. This block uses 1.
By region
Every region of the Half Square Triangle block, the units it needs, and what they are cut from
RegionUnitsCut from
Light Triangle16⅞" square, cut once on the diagonal
Dark Triangle16⅞" square, cut once on the diagonal

How it goes together

  1. Step 1

    Cut your pieces

    Cut the pieces in the cut list. The sizes are for a 6 inch finished Half Square Triangle block and already include a quarter inch seam allowance.

  2. Step 2

    Make the half-square triangle units

    Sew each pair of triangles along its long edge and press toward the darker fabric. Trim every unit to size before you join it.

  3. Step 3

    Assemble the block

    Join the units into rows, then join the rows. Press as you go and square the finished block to size.

Try the Half Square Triangle on a real layout.

Open it on the Design Wall. Try a few colors, see the math, change your mind.