Make Eight Half-Square Triangles


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If you haven't seen this method before - get excited! This is a very fast way to make half-square triangles eight at a time. This saves so much time in my opinion. 



1. Cut your squares. 

There is a simple way to calculate what size your starting squares should be. You will need one for the background and one for the triangle. If you know the size of your finished half-square triangle all you have to do is add ⅞" and multiply times two.

For example - if you want your finished block to be 4 ½" x 4 ½" your formula will be:

4 ½" + ⅞" = 5 ⅜"

5 ⅜" x 2 = 10 ¾" 

So cut one square from each fabric that is 10 ¾" x 10 ¾" 



2. Align your squares and mark them an "X".

Line up your two squares and using a temporary marker, draw a line from corner to corner to make an "x". Add a few pins to keep your pieces in line. 




3. Sew ¼" on either side of each line.

That means you will be sewing four lines across your fabric. Sew outside the line not on the line. 



4. Cut apart.

First, find the center of each side of your square by finger pressing in half in both directions. 


Cut along the center + that you just created with your finger pressing. I do the vertical and then the horizontal. I also like to use my cutting mat with the centers aligned somewhere on the grid. 



Next cut along the diagonal lines your drew with your temporary marker. 




5. Press open and trim!

Press your seams open and trim your squares so you get nice straight edges. You have eight half-square triangles!





There you have it! Eight beautiful half-square triangles all ready to sewing into your quilt. If you want to practice your new skill you can give The Playroom Quilt Pattern or the Desert Flight Pillow a try. 

Happy Sewing!!


Next you might also enjoy these blog posts:

Sewing Triangles

Chain Piece Sewing

The Playroom Quilt Pattern



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  • susan on

    I knew there had to be a faster way —I’d just never seen it until today, in this half square triangle explanation!
    Fantastic, thank you!!

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