Half square triangle unit

Half Square Triangle from strips

1 - 3 inch unit from 44 inch fabric bolt width

There are several methods to make half square triangles. Following are instructions to make half square triangles from strips. To calculate how large to cut strips, add 1/2 inch seam allowance to what you want finished unit size to be. Below calculations are made using this formula.


Unit size
Number of units
Fabric bolt width


Fabric 1
Cut 1 - 31/2 inch strip.
Fabric 2
Cut 1 - 31/2 inch strip.


Half square triangle from strips
  • Match 1 strip of each fabric right sides together.
  • Using a side right triangle ruler or template, cut half square triangles. Move ruler/template upside down for next cut when necessary.
  • Sew 1/4 inch seam on long side of triangle pair.
  • Press seam to one side.
  • Makes 1 half square triangle units.