half square triangles to make into quilt blocks
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Half Square Triangle Table Runner

The Half Square Triangle

Half Square Triangle Table Runner

The half square triangle (HST) is a versatile piecing method that forms to create so many quilt blocks. We’ll explore several easy blocks using the half square triangle to close out National Quilting Month. Choose your favorite and make a table runner with pretty quilting.


What is a half-square triangle? It’s a square quilt block made of two triangles, pieced along the long triangle edge. This edge is cut on the bias, making it a bit stretchy and unwieldy to sew. It’s easiest to sew two at a time from two fabric squares, and then cut after sewing is complete.

two half square triangles

How many quilt blocks can you make using HSTs (half square triangles)? So many quilt blocks are formed using half square triangle blocks. Here is a small sampling of simple blocks made from HSTs:


Pinwheel Block made from half square triangles


Flying Geese quilt blocks from HSTs


bowtie hourglass from half square triangle blocks


Square in a Square block


Create all sorts of different quilt blocks simply by turning the direction of the HST units. These mini blocks combine to make much more intricate blocks, too. But the foundation is the HST unit.

four half square triangle units

How do you sew a half square triangle block? First, determine the desired finished block size and add ⅞” to determine the square sizes to cut. Each fabric square pair will create two HSTs. Here is a chart for easy reference to get you started. To create HSTs larger than 4 ½”, shown below, simply add ⅞” to the square size.

half square triangle cutting chart


Now, cut two fabric squares to the determined size. The featured fabric squares are 4⅞”, so they combine to create two half square triangles measuring 4″ after sewing.

two fabric squares to make HSTs

To begin, place the fabric squares right sides together on a flat work surface, aligning all corners and edges. Using a fabric marking pen, draw a line from one corner to the other to divide the upper fabric square into two right triangles. Then, mark a line ¼” from the centerline on both sides. (A quarter-inch ruler is great for this step.)

marking sewing lines for half square triangles

Next, sew along the outer marked lines from the same direction. Note: in the image below, there is no marked centerline because a specialty ruler was used that eliminated this step.

sewing marked lines for half square triangles

Then, use a rotary cutter and self-healing cutting mat to slice down the centerline (if using) or along the center of both seamlines from corner to corner.

Then, press the seams toward the darker fabric.

two half square triangles

Next, trim the blocks, and then arrange as desired.


Use the half- square triangle blocks to create a pretty table runner, accented with fun quilting. This table runner consists of three rows of ten blocks. It measures approximately 12 ¼” x 31″. Table runners can really be any length, so determine the size you desire for your table and proceed with arranging half-square triangle blocks to create a pleasing design.

For the featured table runner, the blocks are arranged simply to highlight the half-square triangle block.

After sewing the blocks together, create a quilt sandwich with the backing fabric wrong side up, batting, and then quilt top right side up. THen, secure the layers with Sulky KK 2000 Temporary Spray Adhesive.

half square triangle table runner spray basting with KK 2000


The featured table runner was pieced with Sulky 50 wt. Cotton Thread. This lightweight thread is great for less bulky intersecting seams. It’s also nice for quilting, when you want the quilting stitches to blend in with the fabric and be almost undetectable.

However, for this quilting to stand out and add more color to the finished piece, we’re using 30 wt. Cotton Blendables®. This thread is heavier weight and sits atop the quilt surface to showcase the stitching. Plus, it is randomly dyed every 2½” to 5″ across the thread length. So, there are no repeating patterns in each subsequent row of stitching. The thread literally BLENDS to create an almost watercolor effect.

30 wt. cotton blendables thread

Next, quilt the half square triangle table runner as desired. The featured table runner was quilted with a wavy serpentine stitch on the sewing machine, every ¼” to ½” across the piece, diagonally to match the diagonal seams of the HSTs. The stitch length was very small to mimic the look of a bead stitch. Sulky 50 wt. Cotton Thread was used in the bobbin, in a color that matched the backing fabric.

quilting the table runner


When the quilting is complete, trim the table runner so all edges are even. Be careful to not trim off the corner points of any of the blocks.

quilting on the table runner

Lastly, bind the table runner in the manner of your choice.

binding the half square table runner

Now, experiment with different simple table runner designs, simply by changing the direction of half square triangle blocks! These table runners make great gifts and are good scrap-buster projects. After scrap hunting, combine all sorts of different fabrics to create different looks.

finished table runner using half square triangle blocks

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I am the Director of Content for Sulky of America. The former Editor in Chief of Sew News and Creative Machine Embroidery magazines, I hosted Sew it All TV on PBS for nine seasons. I've appeared on It's Sew Easy on PBS, DIY Network's Uncommon Threads, Hallmark's Marie Osmond Show, MacPhee Workshop and more! Come sew with me!


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