Square Peg Quilt Block Tutorial + Tips & Tricks

This blog post introduces the Square Pegs quilt block, a playful design built around a centered square surrounded by four half rectangle triangles. Using fabrics from Benartex’s Cozy Cats collection, the post explains the process of creating half rectangle triangles from rectangles, determining the size of the center square, and assembling the block using a partial seam technique. Although the method may feel unfamiliar at first, the step-by-step approach shows how the pieces come together smoothly, opening up new possibilities for creative quilt designs.

I call this quilt block Square Pegs because the design has a slightly wonky look, with angled shapes surrounding a straight square center. It reminds me of the old saying about fitting a square peg into a round hole, or the other way around. This technique was completely new to me, and I will admit that at first my brain struggled to understand how it all fit together. I even had to call my sister Janet from the Kettle Country Quilters in Plymouth, Wisconsin, to talk me through it. Thank you, Janet. She tried explaining it by text, but eventually we talked it through on the phone, and the whole process finally clicked.

The fabric I used for this project comes from the Cozy Cats collection by Benartex Fabrics, which we will link in the description. If you look closely at the center of each block, you will notice a small cat face, which adds a fun little detail to the design. For the demonstration I made the blocks slightly larger than I normally would so the steps would be easier to see.

Each block is made from four pieces called half rectangle triangles. If you are familiar with half square triangles, this is a similar concept but made with rectangles instead of squares. The rule I follow when cutting rectangles is that the length should be twice the width. For example, you might cut pieces that are 3 by 6 inches, 4 by 8 inches, or 5 by 10 inches. In this case, I started with rectangles that measured 4 by 8 inches. One piece is a background fabric, which I chose in black, and the other is the print fabric.

To make a half rectangle triangle, place the two rectangles right sides together and draw a diagonal line across the top piece. Instead of sewing directly on both sides of that line in its original position, rotate the pieces slightly so the points shift. It will look a little strange and uneven, but this adjustment is important. Once rotated, sew a quarter inch on both sides of the diagonal line, cut along the line, and press the pieces open. The finished half rectangle triangles will measure about 3 by 6 inches. You lose some fabric during this process, but you gain two usable units from the pair.

For each block, you need four of these half rectangle triangles. When you place them together, you will notice that they create a space in the middle that needs a square. To determine the size of that center square, lay the pieces out and measure the opening. In my case the opening measured about 3 inches, but because quilt blocks require seam allowances, the center piece needed to be cut at 3 and a half inches.

This is where the piecing process becomes a little different from most quilt blocks. Normally we work in full rows or columns, but this design does not allow that. The key is to attach the center square to one of the half rectangle triangles first. Align the edge carefully and sew only from a quarter inch inside the edge to a quarter inch before the end. This partial seam is critical because it allows the rest of the block to come together later.

After that first seam, you can attach the next half rectangle triangle along the long edge that has been created. Continue adding pieces one at a time, almost like building a log cabin block. When you reach the final piece, you will fold back the small unstitched section from the first seam, which allows the last triangle to be sewn into place.

Once the final seam is completed, you can finish the partial seam you started at the beginning. Open everything up, press it flat, and the block comes together perfectly with that square center surrounded by the angled pieces.

This technique was new to me, but I really enjoyed learning it because it opens up a lot of possibilities for future quilt designs. If you have never worked with half rectangle triangles before, this is a great way to explore them. I hope you will give it a try. Follow us on Facebook, subscribe to our YouTube channel, and as always, happy sewing.