Half-Square Triangles, Two at a Time Math Explained - Make Them Any Size

Half-square triangles are probably the most versatile quilt block out there. You can make individual blocks with them or even an entire quilt from them. Once you know how to figure out how to make them the quilt world is really your oyster.  There won't be anything stopping you!  Today we are focusing on making them two at a time.  We'll cover how to figure out what size to cut your starting square, two methods for marking your squares for sewing, and then trimming your half-square triangle to the right size.

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This is the first post in our series on half-square triangles.  I have done a new video for the magic 8 method going a little more in-depth than I did previously (new video released 3/24/2020), we will also cover from bonus triangles (video/blog post released 3/31/2020), and paper piecing (video/blog post released 4/7/2020).  There are other methods for making half-square triangles than just these four methods.  These are the four ways that I make them.

Making Half-Square Triangle Two at a Time

This video will be the longest of the series.  Having the basics down from the two at a time method really helps with the other methods of making half-square triangles.  So ready to dive in and learn how to make some half-square triangles two at a time?



That wasn't too bad, was it?  If you would like more information on making the tape guide check out this blog post.

We are offering a handy worksheet for free.  The worksheet includes both the 7/8 method and the 1" method for figuring the size of squares you need to cut. You are welcome to print this sheet as often as you need.

Tips For Making Half-Square Triangles

No matter what method you plan on using to make your half-square triangles there are a few things to keep in mind.

When you see HST in a pattern or tutorial know that means half-square triangle.  Quilters have their own language but we sometimes forget to share that language so that newer quilters know what we are talking about.  If you are a new quilter be sure to check out our posts to designed to get you off on the right foot.  If no one has said it, welcome to the family! 

You do not have to use the method that is listed in the pattern you can pick the method that works for you.  Know that you will have to adjust the amount of fabric that the pattern calls for. 

Oversizing and trimming to size might seem like a waste of fabric but trimming down allows "shift to happen" without wasting a bunch of fabric.  A little trimming is better in my opinion than block after block that can't be used.  

If you use a longer stitch length when piecing keep in mind the size of your half-square triangles.  Little triangles and a long stitch length could mean just a few stitches holding it together.  If needed shorten your stitch length.  I normally stick to a 2.5mm for my piecing.

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