Half square triangle quilt blocks, also referred to as HSTs, are used in traditional, modern and contemporary quilts. They can be made in any size, and there are a variety of methods to make them. HSTs are used in hundreds (if not thousands) of traditional quilt blocks. In this article, we’ll show you the step-by-step method for making half square triangles two at at time.

It’s almost easier to make two half square triangles at time, than to make only one! It’s super easy and you are not matching two bias edges that can stretch when cut.

With this method, you are handling fabric cut on grain and only sewing two seams on the bias and then cutting apart to make two half square triangles.

As an Amazon Associate I earn from qualifying purchases. Read more about our affiliate linking policy.

Half Square Triangles Two (2) at a Time Calculator:

If you want 3″ finished blocks, start with 3-7/8″ squares. Always cut your fabrics 7/8″ larger than the finished block size. The calculation is (finished size of square + 7/8) = cut fabric for 2 half square triangles.

1″ finished block, cut 1-7/8″ squares
1-1/2″ finished block, cut 2-3/8″ squares
2″ finished block, cut 2-7/8″ squares
2-1/2″ finished block, cut 3-3/8″ squares
3″ finished block, cut 3-7/8″ squares
And so on . . .

Makes Two (2) quilt blocks

How to Make Half Square Triangles Two at a Time

Prep Time: 10 minutes

Active Time: 20 minutes

Total Time: 30 minutes

Half square triangles are used in traditional, modern and contemporary quilting. This easy method makes two half square triangles at once.

Materials

Fabric large enough to cut out your squares
Coordinating thread

Tools

Rotary cutter
Rotary rulers
Rotary cutting mat
Sewing machine
Iron
Ironing board
Marking pen; I used a Frixion pen

Instructions

Start by cutting out two squares each 7/8" larger than the finished final square size. See chart above for common sizes. Mark the center line on each with a fabric marking pen or pencil. I like to use a Frixion pen.
Using a 1/4" foot on your sewing machine, sew along one side of the marked line.
Turn the piece and sew 1/4" along the other side of the marked line.
Here is the piece with both sewing lines on either side of the marked line. Cut down the center line forming two half square triangles.
Press open and you have a perfect half square triangle quilt block!