Quilting Lesson: How to Make Half-Square Triangles for Quilting

When you're quilting, you'll frequently find a need to have quilting squares made out of two triangles. Here's a technique to make half-square triangles quickly and easily.

To make your half-square triangles you'll need to start with two squares of fabric that are the same size. For my example, I used squares that were three and seventh eights inches square. When completed, it will make two half-square triangles, each of which is three and one half inches squared.

Begin by taking your two squares of fabric, and placing them with the good sides together. The good side of the fabric is the shiny side or the more vibrant side. It's the side that you want to show later. If you're stacking them on your table, you put the first one down good side up, and the second down good side down. That way the good sides are touching each other.

Using a ruler, draw a pencil line diagonally across the square, from corner to corner. You can do it on either fabric, but I suggest you do it on the lighter of the two, so that it will be easier to see while you're working.

Using your quarter-inch foot, make two straight stitch-lines diagonally through your two layers of fabric squares. One line of stitching should be a quarter-inch to the left of the pencil line that you just drew. The other stitch-line should be a quarter-inch to the right of your pencil line. When you're through, you should have two stitched lines, half an inch apart, centered along the pencil line that you drew.

Using a rotary cutter and ruler (or scissors if you're very, very careful), cut through both layers of squares along the pencil line that you drew. You won't need to erase the pencil line because it is going to disappear into your seam allowance in a moment. When you finish, you should have two sets of two triangles with a quarter inch stitched lines along the long edge of each one.

Unfold each set of triangles and iron them so that the seam goes toward the darker of your two fabrics. Now you have two half-square triangles! A bit of your fabric was lost in the seaming which is why instead of being three and seventh eighths inches squared, your finished block will now be three and one half inches squared.

Making your half-square triangles two at a time this way is not only faster than cutting triangles and doing them one by one, it's also easier to stitch because you don't have to hold the long edge of the triangle steady while sewing on the bias. You can use this technique on a whole stack of squares and put out enough half-square triangles for an entire quilt in just an hour or so.

Happy Quilting!

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