Making half-square triangle quilt units four at a time

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

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.


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 the square from corner to corner on both diagonals.

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


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


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.


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

Elizabeth DeCroos

designer, teacher, speaker

Elizabeth enjoys doing all types of sewing and needlework and teaching others new techniques. Find out how to take a course or workshop.

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