dark and light blue fabric pieced triangles with title "half square triangles".

Tutorial for making half-square triangle quilts by strip piecing

Strip piecing half square triangle units is not intuitive, but great if you have strips of fabric to use up.  In this method, you can use fabric that would be too narrow to use with most of the other methods.

Cut fabric strips

Cut fabric strips the same size as the finished piece that you need. For example, if the finished unit will be 4″, then cut 4″ strips, one of each colour.

two strips of fabric.


Lay them right sides together and sew a 1/4″ seam on both edges of the strips.

strips of fabric stitched on both sides.

Cut the triangles

Cut triangles using a triangle ruler or the 45º angle line on your basic ruler.

cutting strips into triangles.
cutting strips into triangles.

Open and press

Gently pop out the stitching at the tip of the triangle.

popping the seam in the tip of the triangle.

This is where the technique gets problematic. If you have a stitch length that is too short, then you need to be very careful unpicking the stitching or the fabric will pull and distort. If you have a stitch length that is too long, then the ends of the seam might pull loose.

Unfold and press.

half square triangle


Trim to size if necessary.

Align the the 45º line from the ruler with the seam line, and trim the edges to the size that you need.

Remember that if you want a finished size of 4″, you need to cut the square 4-1/2″ to allow for a 1/4″ seam allowance.

The triangle units are finished, but treat them gently, as they have bias edges and the tip might be fragile where the stitching was pulled out.

What’s Good

  • quick to stitch
  • easy for small squares
  • great for jelly rolls

What’s Not Good

  • accurate cutting can be tricky
  • bias edges
  • lots of trimming

When to use this method

  • you only have narrow scraps left, but need a bunch of HST units
  • you want to use jelly rolls
  • you are careful with the bias edges

Rating: 2 out of 5

This method is handy if you want to use a jelly roll or some other narrow fabric.  Other than that, I wouldn’t recommend it.  There are lots of other HST methods, and they are all better than this.


blue and white fabric pieced triangles with title "half square triangles".
blue fabric pieced triangles with title "half square triangles".
Elizabeth DeCroos

Elizabeth DeCroos

designer, teacher, speaker

Elizabeth enjoys doing all types of sewing and needlework and teaching others new techniques. For more information or to have her speak to your group click HERE.

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