Quarter square triangles are a basic block you can use alone or combine with other blocks to form more intricate quilt designs. When using only two fabrics, the quilt block is also called the Hourglass Quilt Block. The basic block is four (4) 90-degree triangles sewn together.

Our preferred method to making this block creates two (2) at a time, with the outside edges on straight of grain. To start, we make half square triangles, and then layer them to sew into quarter square triangles. Other names for this technique are the sandwich method, or quick piecing method. This is an easier method than sewing together individually cut 90-degree triangles, and more accurate.

We start with the basic half square triangle. Here is an article that shows you seven (7) ways to make half square triangles.

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Quarter Square Triangle Calculator

First, decide the size of your finished quarter square triangle block. In the tutorial below, we wanted a 3″ finished quilt block. Add 1-1/4″ to the finished size, which gives you the size to cut the pieces. This allows the seam allowances in a finished 3″ quilt block. Here is a handy reference for you:

Quarter Square Triangle Fabric Calculator

Makes Four (4)

How to Make a Quarter Square Triangle Quilt Block

Prep Time: 10 minutes

Active Time: 15 minutes

Total Time: 25 minutes

Difficulty: Easy

The quarter square triangle quilt block is a basic block that can stand on its own or be used in other more intricate quilt blocks.

Materials

Two (2) or more fabrics
Thread

Tools

Marking pen or pencil
Quilting ruler
Rotary cutter
Cutting mat
Sewing machine
Iron
Ironing board

Instructions

Cut two squares of fabric 1-1/4" larger than your finished block size. I cut 4-1/4" blocks for a finished quilt block size of 3".
Mark the centerline on the wrong side of one of your blocks. This will guide your stitching.
Layer your fabrics right sides together with the marked fabric on top. Stitch 1/4" from the marked line.
Turn and stitch 1/4" from the other side of the marked line.
Cut along the marked line, making two triangles that will press open to squares.
Press seam. See article on pressing seams for more information. Lay your blocks side by side as in this picture.
Flip one square over the other, right sides together, so that opposite colors are layered.
Mark a centerline on the top block. This will be your guide for sewing the next seam.
Sew 1/4" from the marked centerline.
Turn and sew 1/4" from the other side of the centerline.
Cut along the marked centerline.
Press seams. You now have 2 finished quarter square triangle quilt blocks!