Making Half-square Triangles with the 8-at-a-time Method
A half-square triangle unit is a square made by joining two right angle triangles on the diagonal. Often half-square triangle units are used in multiples of four, so making eight at a time can be helpful.
There are many different methods for making half-square triangles, so if you have trouble with this method, you can check out these alternate HST techniques.
You can use this shape to make blocks like pinwheel, shoo fly or friendship star.
See it All
Below you will find:
- video tutorial
- step-by-step written tutorial with pictures
- quilt blocks with half-square triangles
- quilts with half-square triangles
Video
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Tutorial
See each step in the process, with images to help guide you.
Cut squares
You will need two identical squares of fabric, one of each fabric you are using.
To calculate the size of square, take the finished size of unit you want (without seam allowances), then add one, and then double that sum.
For example, if my HST units to be 4″ in the finished quilt, then I want the squares to be 10″. (4 + 1 = 5 and 5 x 2 =10)
Mark the squares
On the back of the lighter square, mark the centre lines horizontally and vertically and mark lines from corner to corner.
You can use an erasable marker, pencil or permanent marker, since these lines will be trimmed later.
Stitch
Stitch 1/4″ away on both sides of the diagonal lines.
(Don’t stitch on the vertical or horizontal lines.)
Cut
Cut the piece on all four lines – diagonal, horizontal and vertical.
This will give you eight half-square triangle units.
Press
Press the pieces so that the seam allowance goes under the darker fabric.
Trim
Trim the half-square triangle unit down to the size you need. This will be the finished size plus 1/2″ for seam allowances.
So, from the example, if I want my HSTs to be 4″ in the finished quilt block, I will trim them down to 4-1/2″.
Use half-square triangles in quilt blocks
These blocks will help you be creative with half-square triangles.
Use half-square triangles in quilts
These beautiful quilts use half-square triangles.
Making Memories
This two-colour quilt is made with only squares and half-square triangles.
Scrappy Twinkle Quilt
This quilt is a scrappy version of the Twinkle Sampler Quilt.
No Flies in my Garden
This quilt has shoo fly blocks outlined by squares.
Nine Patch Sampler
This is the pink version of the Nine Patch Sampler quilt.
You can get free instructions and make your own Nine Patch Sampler.