Quarter Square Triangles: easiest method ever

red and white quarter square triangle with title.

Quarter square triangles are triangles that are made by cutting a square into four on the diagonals. They look similar to half square triangles, but there are some differences in how they go together.

If you’ve ever struggled with getting everything lined up and straight, then this is the method for you. It’s the easiest method in the world and it works perfectly every time.


For this method, you will need four squares of fabric. Each square will become one of the triangles, so you can use two colours or four, whichever you prefer. Traditionally two triangles are light and two are dark.

Cut the fabric squares the same size that you want the quarter square unit to be.

For example, if you want the finished unit to be 4″ square in the quilt, then you want the unit to be 4-1/2″ square to allow for seam allowances. This will mean cut the squares 4-1/2″.

four squares of fabric.


On the wrong side of the lighter squares, mark a line from corner to corner.

marking fabric squares for quarter square triangle.

Place two squares right sides together.


Stitch the squares together, stitching on the marked line.

squares stitched for QST.


Trim 1/4″ away from the stitched line.

The trimmed corner is excess and can be saved for another project.

making quarter square triangles.

Open and press to the dark side. You now have two half-square triangle units.

half square triangles.


Mark one of the HST units on the wrong side corner to corner and place right sides together with the other HST.

Be sure that the dark side is touching the light side.

joining squares for quarter square triangles.

Stitch directly on the marked line.

easy quarter square triangle construction.


Trim 1/4″ away from the stitching line. This corner is also excess

quarter square triangle in progress.

Open and press.

You’re done!

It’s a perfect quarter square triangle unit.

red and white quarter square triangle.

What’s Good

  • easy math
  • simple
  • no squaring up
  • perfect result

What’s not Good

  • only makes one at a time
  • fabric waste

When to use this method

  • when making really small squares
  • if you struggle with math
  • if you need an odd size
  • when you’re in a hurry
  • if you only need one

Rating: 3 out of 5

This method is fine if you are just doing a couple of QST units, but if you were making a whole quilt full of them, it would be time consuming and wasteful.

assorted pieced triangles with title.

blue and white flying geese unit with title.

Elizabeth DeCroos - Epida Studio.

Elizabeth DeCroos

Elizabeth DeCroos is the designer and teacher at Epida Studio. She loves to work in quilting, pojagi and embroidery and teach these techniques to others.
Learn more and get her to speak to your group.

Scroll to Top