How to Make Half-Square Triangles

I realize that there are several methods for making half-square triangles and even more tutorials already on the internet. However, I had a friend ask me how to make them, so I thought I'd take a few step-by-step pictures of the method I like to use most often.  

Start with two squares of contrasting fabric. In this example, my squares measure 3 1/2 inches. We'll get two half-square triangle blocks from this one set.

Place right sides together, and draw a pencil line across one diagonal, from corner to corner.

Stitch 1/4 inch on either side of the pencil line.

Cut along the pencil line.

"Set the seam" by pressing the halves before opening them up. Press the seam open toward the darker fabric. 

Trim the edges of your half-square triangles so they are perfectly square. In this example, I trimmed them to measure 3 inches.

Tip: For perfect corners in your quilt design, make sure that the seam in your half-square triangle hits the corner perfectly. (In math class, we would call the seam an angle bisector!)
Have fun with your squares! These are a just a few designs I thought of, but the possibilities are endless. Look what you can do just by changing the color and placement of your fabrics!

Next time, let's tackle quarter-square triangles.


  1. so helpful...someday I'll have a knack for quilts. That day has definitely not arrived yet. Can't wait for your Riley Blake tutorial! Hope you got some free fabric :)


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