blue fabric pieced triangles with title "half square triangles".

Making half-square triangle quilt units four at a time

Some quilt designs require a LOT of half-square triangle units.  In that situation, it can be nice to make a bunch at a time.  This method lets you make four at a time.

Cut squares of fabric

For a 4″ finished unit, begin by cutting two 7-1/4″ squares.

two squares of fabric - dark and light blue.

Mark the corners

Mark 1/4″ in from the corners on the wrong side of one of the squares.  This step is optional, but helpful especially if it’s your first time trying this method.

hand marking a 1/4" seam allowance on a square of blue fabric.

Stitch

Put the squares right sides together and sew all the way around the square with a seam 1/4″ from the outer edge, using the marked corners for accurate turns.

Pinning the squares together with help them not to shift while you are stitching them.

a square of blue fabric with stitching 1/4" away from the edge all the way around.

Cut

Cut the square from corner to corner on both diagonals.

fabric square being cut on the diagonal with a rotary cutter and quilting ruler.

Press

Unfold and press and you have four half square triangle units.

Trim

They will be a bit big, so a little trim will make them the perfect size as well as removing the dog ears.

Align the diagonal seam with the 45* angle line on the quilting ruler. Cut off a bit to make sure the edges are straight. Then turn the piece and trim the other corner to make it the exact size.

trimming a fabric square made up of two triangles sewn together.

There you go!

four fabric squares made by sewing together a light blue triangle and a dark blue triangle.

What’s Good

  • fast
  • makes 4 at a time
  • little waste

What’s Not Good

  • bias edges
  • squaring up is tedious
  • sometimes squares shift during stitching

When to use this method

  • patterns require a lot of HST units
  • you use a lot of starch before cutting

Rating: 2 out of 5

I know many people love this method, but I don’t prefer it.  I don’t think the pros outweigh the cons. Bias edges stretching during construction can be fatal to a quilt.


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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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