Sew Half-Square Triangles Easier (and More Accurately!)

Half-square triangles are a common quilting unit, so you'll likely sew them for many patterns in your quilting life. But they're not always the easiest or most fun to sew. I'm sharing my top tips for sewing half-square triangles, including some of my fave products, so you can conquer this popular block!

5 Tips for Making Triangle-Squares

Mark Accurately

When your pattern calls for marking a diagonal line on the wrong side of your fabric and then sewing 1/4" away from the line, make as skinny of a line as possible. If your line is thicker, it can affect the accuracy of your sewing and the finished size of your half-square triangles. I suggest using a thin pencil or hera marker to mark those diagonals. And watch my video below to see my best marking tips and techniques!

Buy a hera marker on Amazon or Fat Quarter Shop.

Give an Extra Press

Before pressing your half-square triangle open, set the seam with an iron. To set the seam, press along the stitching line, which allows the thread to sink into the fabric for a clean diagonal seam. I press my half-square triangles from the right side (front) to eliminate any accidental tucks or folds in the seam.

Oversize Your Triangle-Squares

Some patterns will call for you to cut your squares at a measurement that ends in 7/8" or 3/8", which means if you sew accurately, your triangle-squares will finish at the exact right size. Many quilters choose to oversize their squares by at least 1/8" and then trim them to the right size after sewing, so they can be sure their blocks are accurate. But trimming can be time-consuming without the right tools. We suggest getting an acrylic ruler meant for trimming half-square triangles to make the trimming process easier.

My favorite rulers for this are the Clearly Perfect Slotted Trimmers from New Leaf Stitches. These rulers are so handy and can trim half-square triangles in a variety of sizes. You simply line up the line on the ruler with the stitching line, trim along the two sides of the ruler, and trim inside the notches to eliminate the dog ears.

Buy the Clearly Perfect Slotted Trimmers on Amazon or Fat Quarter Shop.

Give It a Spin

You can also make trimming oversized half-square triangles easier with a rotating cutting mat. The mat spins, so you can trim on all four sides of the block without needing to reposition your block, ruler, or body. I love my OLFA 12" rotating cutting mat, which as a bonus, fits inside many standard project bins, so you can easily take it to a retreat.

Buy the OLFA cutting mat on Amazon or Fat Quarter Shop.

Sew with Triangles (Instead of Squares)

Although the 2-at-a-time half-square triangle method is very common, it has a lot of tedious steps and leaves room for error. I often use a method that saves time and is easier for me. Instead of marking a diagonal line on my squares and then sewing on either side of the line, I skip this step and just cut on the line instead. This saves me a bit of time and also gives me the advantage of being able to sew the triangles together with my 1/4" guide in place.

I hope these tips help with your half-square triangles! Looking for a pattern to put these tips to the best?

Try my Bear Necessities pattern--the pattern has tips for making triangle-squares three different ways.

Thanks for joining me for "happy hour",

Lindsay

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