Use the The Magic 8 Method and Make 8 Half-Square Triangles at Once

Magic 8 Half-Square Triangles

If you don’t like cutting and stitching loose triangles together on the bias, you’re not alone. Making enough half-square triangles for a quilting project can get totally tiring. But don’t fret — here’s a quick and easy solution to your HST woes.

The Magic 8 Method

Level: Easy

1. Determine Size

First you need to know what size finished half-square triangles are desired.

For example:

  1. Let’s say you want to make 3” finished half-square triangles.
  2. Add ⅞” to your 3″ measurement.  (Your total is now 3⅞”).
  3. Multiply your total of 3⅞” by 2. (That equals 7¾”).
  4. 7¾” squares are the size needed to make your 3” finished half-square triangles.

2. Cut

Cutting Two Squares to Make Half-Square Triangles

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

3. Mark

Drawing Diagonal Line on Fabric Square

Place the two squares on top of each other, right sides together. Draw two diagonal lines corner to corner on the top fabric.

4. Stitch

sewing for magic 8 hst method

Stitch a total of four lines: two on both sides of each diagonal line, ¼” away from the line.

5. Cut

Cutting Fabric Square in Half Vertically

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.

Cutting fabric square horizontally

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 are better positioned to make the cut, or turn your cutting mat.

cutting fabric square diagonally

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. Open and Press

finger pressing a gray and purple half square triangle

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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33 Responses to “Use the The Magic 8 Method and Make 8 Half-Square Triangles at Once”

  1. Susan Short

    Love the fact you gave us the formula for sizing the half square triangles, thank you.

  2. Jacqui

    Thank you for this amazing tip. Been wanting to start a quilting project but wasn’t sure how to start. This has spurred me on to get sorted & start

  3. JBK

    Just finished making a bunch of hst’s for our small quilt group. Might have saved some time if we had done this! TY

  4. Dr. Yasmin Akhtar Kazi

    OMG, so easy way of cutting triangles. Hats off dear. You made my day.i will try to cut triangles as you explained.😍😍😍😍

  5. Carol A Skilling

    What a great way to do this! 8 at once! I will have to do this! I like that the math has been figured out. Thank you very much! Carol

  6. Diane

    Great technique but how did you come up with the “7/8” measurement to add to your 3” size triangles?


    This method has been around for a while and much better than the one on Missouri Star that leave you will bias edges.

  8. JoAnn

    Say I want to make six inch triangles how big would my fabric have to be to make four at a time?

  9. Margaret

    I am a 9th grader, and I made a quit last year and I wish I knew this trick! I will remember it for future projects!

  10. Nellie Lara

    I have always wanted to know how to quilt. It is interesting. But this technique was such a neat trick. It can be used for almost anything you want to do. Wow, I love it. It may inspire me to try to do something later. Thanks This was like a genius thing for me. I’m so new to this stuff so I had to look at it several times, then it was like, that was cool. Simple yet so neat.