Quilt Class: Making Half Square Triangles

Some time ago, I saw an episode of Love of Quilting where Jo Morton was the guest. She was showing a technique for making half square triangles that blew my mind. Based on what I saw Marianne and Jo do on the show, I tried the technique and was pleased with the results.

I found this half square triangle (HST) technique to be one of the best I have seen. It is straightforward, there is a minimum of dealing with bias and the squares magically appear all at once.

There are a number of different tutorials for making HSTs (half square triangles/triangle squares) and I link to some of them below. My technique below makes 8 HSTs at a time and can be used for the Double Pinwheel that is part of the Quilt Class tutorials.

This is more of an informational tutorial than a tutorial related to certain blocks. HSTs are a component in many, many blocks designs, so learning to make HSTs using this method will come in handy

I started with 5″ squares, which is the size they used on the show. The 5″ squares make 8 HSTs. I thought it would be a great way to use charm packs. For other sizes, I have created the AQ HST Size Chart. You need this chart to find the sizes of the various pieces to make other block patterns.

Supply list:

  • AQ HST Size Chart
  • fabric
  • rotary cutter
  • rotary cutting ruler large enough to cut 4.5″ squares
  • rotary cutting mat
  • fabric (2 different)
  • Optional: Mary Ellen’s Best Press (or similar)
  • pins
  • sharp trimmers or scissors
  • thread for piecing
  • sewing machine
  • Iron
  • ironing surface
  • Sewline pencil** or mechanical pencil
2 5
2 5
Draw an X
Draw an X
Put 2 squares together
Put 2 squares together

First, I cut two squares according to the AQ HST Size Chart.

Next, using a ruler and my Sewline pencil, I drew an X, corner to corner, on the lighter square.

Place the 2 squares right sides together and press them.  Pin far away from any of the lines.

Next, sew 1/4″ away from each line. I place the guide of my 1/4″ foot on the pencil line, which ensures my needle is 1/4″ away. Sew on both sides of all of the lines.

Measure 2.5" from the edge
Measure 2.5″ from the edge

After sewing, I measured 2.5″ from the side of the square and cut. Don’t move the two pieces. Position your ruler 2.5″ from bottom and make another cut.

Cut in a PLUS Configuration
Cut in a PLUS Configuration

Cut the square in a plus configuration 2.5″ – use the middle of the X as a guide. This is called the PLUS cut on the chart. You can draw pencil lines in a plus configuration and cut on those, if you want.

Cut in PLUS, then X
Cut in PLUS, then X

After you cut the PLUS you will have four squares, each with a line drawn diagonally across the middle. Cut the squares in half diagonally on the line. Use the line as a guide. It is more important to line your ruler up corner to corner.

HSTs from 5" squares
HSTs from 5″ squares

The result is 8 2″ half square triangles. The above are actually a thread or two larger than 2″, which leaves the perfect opportunity for trimming to make them an absolutely perfect 2″. If you trim, you get rid of the bunny ears as well.

Trim on all four sides
Trim on all four sides

Trim the squares to 2″. Line the 45 degree angle line on your ruler up with the diagonal seam line on your HST and trim on all four sides. Trim on all four sides. Don’t be tempted to trim just on two sides.

Beautiful HSTs
Beautiful HSTs

Now you have 8 beautiful HSTs. The bias edges shouldn’t be scary for you when you use the regular HST method, but this method makes HSTs much easier. This is a fabulous method when you need to make a lot of HSTs in a short amount of time. It is similar to a tutorial that p.s. i quilt posted, but times 4.

My DH came up with a chart showing the different sizes you can make with this technique. Look at this chart to find the correct size for your project.

AQ HST Size Chart


  1. Jo Morton website
  2. Jo Morton blog
  3. Jo Morton on Andover
  4. Wet Canvas tutorial
  5. Carole’s Quilting Adventures tutorial
  6. B’s Modern Quilting Fish Tutorial
  7. p.s. i quilt HST tutorial








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