Magic Triangle Quilt Block Directions

Many quilt block patterns are made with half-square triangles
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A magic triangle quilt block utilizes a sewing technique that creates half-squares used in many quilt block patterns.The technique produces many half-squares in a shorter amount of time than a traditional method and with more consistent results. In the past, many quilters cut out triangles and sewed them together, but their blocks end up stretching out of shape or had uneven seams, resulting in uneven blocks. A special half-square ruler helps quilters creates perfect half-square triangles.

Things You'll Need

  • Straight Pins
  • Scissors
  • Rotary Cutter
  • Half-Square Ruler
  • Fabric
  • Self-Healing Cutting Mat
  • Iron
  • Fabric Pencil

Choose your quilt block pattern and fabrics. Determine the number of half-squares needed for each block. A half-square is a block made of two triangles, sewn together, creating a square.

Choose the finished block size by using the ruler markings. Layer two pieces of fabric with right sides together on a self-healing cutting mat with the lighter fabric should on top. Line up the fabric corners and edges. Place the ruler on the fabric, aligning the desired square size with the fabric edges. Cut out the square, using the rotary cutter.

Draw lines on the fabric through the slots in the ruler with a fabric marker. Remover the ruler, you should see lines on the fabric. Pin the squares together with straight pins.

Sew seams on the two outside pencil lines and cut along the inside line. You now have two squares made of the triangles. Open each square and press the seam toward the darker fabric with a hot iron. Trim the excess fabric sticking out on the ends of the seam with scissors. Repeat all steps until you have sewn all the squares you need for your quilt or sewing project.


  • Hold your fabric marker at a 90-degree angle to your fabric for best results.


  • Always handle rotary cutters with care as the blades are extremely sharp.