How to Make 8 Half-Square Triangles at Once: The Magic 8 Method

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Hands up if you'd LOVE to be able to skip the fabric cutting and fast-forward right to sewing your quilt. (Tell me I'm not the only one!) That can't always be a reality, but there are a lot of tricks that can make cutting so much more efficient. One favorite hack: The magic 8 method, which will help you cut and sew 8 half-square triangles at once. Win!

Making the Magic 8 work for you

1. Figure out sizing

This step requires a little bit of math. Start by figuring out how large your finished half-square triangles need to be, then follow this formula:

  • Let’s say you want to make 3” finished half-square triangles.
  • Add 7/8” to your 3" measurement  (Your total is now 3-7/8”)
  • Multiply your total of 3-7/8” by 2. (That equals 7-3/4”)
  • 7-3/4” squares are the size needed to make your 3” finished half-square triangles.

2. Cut your squares

Cut two squares the desired size based on the formula above.

3. Section out the squares

Place the two squares on top of each other, with right sides together. Then, on one of the fabrics, draw two diagonal lines corner to corner.

4. Stitch Your Lines

Next, you'll stitch a total of four lines: one on each side of each diagonal line, ¼" away from the line.

5. Cut out the triangles

Now, you can carefully cut the sewn square into the eight HSTs. You'll make a total of four cuts:

Cut 1:

Cut vertically right down the center. Align your ruler with the center where you drawn lines intersect and one straight edge of the fabric squares.

Cut 2:

Make a second cut that's perpendicular to the cut you just made. At this point, it's best to leave the fabric pieces where they are — don't try to rotate the fabric! Instead, walk around your table so you're better positioned to make the cut, or turn your cutting mat.

Cuts 3 and 4:

Cut on both of the drawn diagonal lines, between your stitching lines. Again, it's best not to move your fabric; instead, move your body or your board so that you don't shift the fabric.

6. Separate the pieces

Now that you're done with your cuts, you can separate the cut pieces...

...and open them up to reveal your perfect half-square triangles! Press the seams to the darker side and you're ready to use them in a project.

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How to Make 8 Half-Square Triangles at Once: The Magic 8 Method