Half Square Triangles are a really cool shape in quilting that, in spite of their name, can actually be pieced using squares. A triangle shape you can create without having to actually cut a triangle shape? Sold! Let's learn how to piece it together in this new quilting tutorial:
We're going to make lots of Half Square Triangles for the Friendship Quilt Along! Click Here to learn more about this excellent skill-building block of the month project.
Half Square Triangles are often abbreviated HST in most quilt patterns. While this isn't the only way you can create them, I find it the easiest because you don't have to cut triangle shapes.
This method also maintains the grainline of the fabric so the edges of your finished half square triangles will be on grain. This is important because as you piece other shapes to your half square triangles, they will be easier to piece because all the fabrics are square with the grainline of the fabric.
Some methods of piecing half square triangles result in the edges being cut on the bias, which can create a very wobbly edge that easily distorts out of shape. Not sure what I'm talking about when it comes to grainline? Check out the book How to Piece Perfect Quilts to learn more about the structure of fabric and how it effects our quilts.
Now that you know a bit about this piecing method, let's learn how to piece two half square triangles together!
Step 1 - Stack two squares of fabric right sides together. Mark a diagonal line from corner to corner.
Step 2 - Take the stack of fabrics to your machine and stitch exactly 1/4 inch away from the marked line. Turn the stack and stitch 1/4 inch away from the other side of the marked line.
Step 3 - Cut the pieces apart along the marked diagonal line with a pair of sharp scissors.
Step 4 - Press the seam allowances open first with your fingertips. Be gentle because this is a bias seam and can easily stretch out of shape. Once the seam allowances are pressed open, press the half square triangle again with a hot, dry iron.
Step 5 - Trim the two resulting half square triangles to the correct size. This is the final step, but it can be a bit tricky. First align the ruler so the 45-degree line is lined up with the diagonal seamline on the half square triangle.
Once you trim off two sides, you're ready to square your unit down to the exact size you need for your quilt. Line up the edges of the half square triangle with the lines on your ruler AND line up the 45-degree line on the ruler with the diagonal seam line as well.
Trim down the remaining two sides and your half square triangles are complete and cut accurately to the proper size for your quilt!
Making More Half Square Triangles
This method always results in two triangles created for every two stack of squares you stitch. This makes it fast and easy to piece dozens of half square triangles at once.
There is an additional step I mentioned in the video and that is trimming the half square triangles down so they are straight and square with the diagonal line. Make sure to watch the tutorial video above so you can trim your half square triangles properly.
Now that you know how to create half square triangles very easily, here's a fun free quilt patterns for you to test your new skills!
The Twin Rainbow Star Quilt Pattern uses super sized half square triangles to create these jumbo star shapes.
The best part of this pattern is you get to make two quilts at the same time. Click Here to find this free pattern.
And just in case you're in a hurry, here's an easy info graphic to remind you just how easy it is to piece two half square triangles at a time!