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Sew Triangle-Squares Easier (and more Accurately!)

Triangle-squares (or half-square triangles) are a common quilt block, 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. We're sharing our top tips for sewing triangle-squares, including some of our 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 triangle-square. We suggest using a thin pencil or hera marker to mark those diagonals.

Buy a hera marker on Amazon or Fat Quarter Shop.

Give an Extra Press

Before pressing your triangle-square 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. We press our triangle-squares 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 triangle-squares to make the trimming process easier.

Lindsay's favorite rulers are the Clearly Perfect Slotted Trimmers from New Leaf Stitches. Lindsay says: "These rulers are so handy and can trim triangle-squares 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. It gets me perfect triangle-squares every time!"

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

Give It a Spin

You can also make trimming oversized triangle-squares 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. Elizabeth loves her OLFA 12" rotating cutting mat, which as a bonus, fits inside her project bin, so she 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 triangle-square method is very common, it has a lot of tedious steps and leaves room for error. Elizabeth uses a method that saves time and is easier. She says: "Instead of marking a diagonal line on my triangle-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 hate taking the time to switch out my guide and I find this method to be really accurate."

We hope these tips help with your triangle-squares! Try our Bear Necessities pattern--the pattern has tips for making triangle-squares three different ways, so you can put these tips into practice!

Thanks for joining us for "happy hour",

Lindsay and Elizabeth

This blog contains affiliate links to Amazon and Fat Quarter Shop. We only recommend products we truly use and love. If you use our affiliate links, we may receive a small commission.


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