The half square triangle (HST) is one of the most useful and versatile quilting blocks. It’s also one of the easiest to create, so is perfect for beginners. In this tutorial we’ll look at what they are, an easy method for making them and how to use them to design a quilt.
What are half square triangles?
The HST is a square shaped block, made up of two right-angled triangles of different fabrics. The two triangles join along the diagonal line.
Making half square triangles
There are various methods for making HST’s. Although you can sew two triangles together, it’s easier and more accurate to piece the fabrics together before cutting them. I’ll show you an example of this method below.
You’ll need two different fabrics cut into squares. In this example I’m using two 4-inch squares.
- Take your lighter coloured fabric and place it right side down. Using a ruler and pencil, draw a diagonal line on the wrong side. This line will not show up on the finished quilt block.
2. Layer your two fabric squares with right sides together, and the lighter fabric on top. Align the edges carefully.
3. Sew a seam ¼” either side of your drawn diagonal line. The dashed line in the diagram below shows where you should sew. You can either draw a line to mark where to sew or use a ¼” machine foot on your sewing machine.
4. Using a rotary cutter and ruler, cut along the marked diagonal line.
5. You will now have 2 half square triangle units. Open out each of the units and press them flat. Trim off the small ‘tails’ of fabric.
Using HST’s for a quilt design
Once you’ve mastered this quilt block, you’ll be able to create a variety of quilt designs. Below are some ideas, that use only half square triangles.
Quilt blocks based on half square triangles
You can also create more advanced blocks based on half square triangles to use throughout your quilt. Here are six ideas for different 4×4 blocks.
I hope you found this tutorial on half square triangles useful. We will be producing more block tutorials in the future. In the meantime, if you have any comments, please leave them below.