20 Ways to Make HSTs – Using Magic

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The Magic 8 Method

Half Square Triangle units (HSTs) are squares made up of two triangles. Each triangle occupies half of the square’s space. As you might expect, there are many, many different methods to make those blocks. This tutorial shows you 20 of the most common methods.

First, a glossary.

A finished HST is the size that it is in a quilt. It’s dressed and ready to go to the ball. An unfinished HST is in raw, unclothed form. It will be 1/2″ larger than a finished HST because the size includes a 1/4″ seam allowance.

Finished and Unfinished HST

The “Magic Eight” Method of Making
Half Square Triangle (HST) Blocks

This method works well when you need to make a lot of identically colored HST blocks. Here is an overview of the method. Make a test block first. (My personal preference is to cut the squares slightly too large so that I can square up the HST blocks later on. If you are sure of your 1/4″ seam, you can use
7-3/4″ blocks. ) Here is how to make a test block.

8 HSTs

Assemble:

  • (1) 8″× 8″ Background Square
  • (1) 8″× 8″ Colored Square

On the back of the Background square, draw 4 lines: one vertically through the center; one horizontally through the center and one on both diagonals. These will be your cutting lines.

Graphic showing square and lines for cutting and sewing HST quilt blocks

Place the Background square and the Colored square right sides together. Sew 1/4″ on both sides of the diagonal lines. You will find it easier to chain-stitch these. Sew all the squares diagonally first, going from one block to the next without snipping the thread in between the blocks. When that is done, you can do the other side.

Press your sewn block. Don’t move the iron. Just press with a hot iron in an up and down motion. You want it to lay very flat before cutting.

Graphic Showing Magic Eight Sewing Lines

Cut it apart on the drawn lines. If you cut it apart using a rotary cutter, take care not to move the squares with each cut.

Picture of a Magic Eight square cut 8 ways

When you have all the blocks cut, you will need to square them up. There are two ways you can square up your block. You can place a 3-1/2″ ruler so the diagonal line is directly over the seam and just cut two sides. Or you can press open the block, pressing to the dark, and square it up to 3-1/2″× 3-1/2″.

Quilt-in-a-Day Square Up Ruler
Use the Quilt-in-a-Day Square up ruler to square up an HST block before opening and pressing it by laying the size line along the seam line. When you cut around the edges of the block folded into a triangle, you are automatically squaring up the block.
Creative Grid Ruler
Place the diagonal line of a square ruler on the sewing line of the triangle. By cutting the two sides of the ruler, you are automatically squaring up the HST block before opening and pressing it.
Making a Fussy Cut Sunflower Quilt Block
How to square up a block is all you have is a square ruler. Just match that diagonal line.
Mardi-Gras-Magic-HST-Block
I am a big fan of Fussy Cut rulers. That center X lets me center the ruler on the block. The marked seam allowances help me make sure that the points won’t be cut off.

Download this free chart

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