How to Make and Trim 2-at-a-Time Half-Rectangle Triangles (HRTs)

This month’s featured technique for the May 12″ block at the 2025 BOM Party is all about mastering 2-at-a-time Half-Rectangle Triangles (HRTs). While the steps might feel similar to making half-square triangles, HRTs have a few quirks, especially when it comes to trimming, that can trip you up if you’re not prepared. But once you know what to look for, they’re simple, satisfying, and incredibly versatile in quilt design.

If you’re a visual learner, be sure to check out the full video tutorial on YouTube and follow along with the diagrams included in this post. Let’s get to it!

What Is a Half-Rectangle Triangle?

A half-rectangle triangle (HRT) is just what it sounds like—a rectangle divided diagonally into two triangles. They’re commonly used in modern quilts and are perfect for adding visual movement. But unlike half-square triangles, their diagonal seam doesn’t run at a 45° angle. That’s the key reason trimming them takes a bit more attention.

For our May block, we’ll be using the 2-at-a-time HRT method and trimming the units down to 2″ x 3″ finished size.

The Key to Trimming HRTs Correctly

Because the seam doesn’t run corner to corner at a perfect 45°, your trimmed units will have blunt corners, and that’s a good thing. Your goal is to have the seam line intersect ¼” in from the top, bottom, and sides—this is what preserves your points when sewing the units into your block.

Before we even start sewing, I like to show this with a drawing. Sketch a 2″ x 3″ rectangle and mark dots ¼” in from each corner. Now draw a line connecting opposite dots. You’ll notice the seam line doesn’t run on a 45°, and that’s why we focus on aligning it with these marks instead of trying to match a diagonal line corner-to-corner like with HSTs.

Also note: you’ll be making HRTs in two fabric arrangements. Half will slant one direction, and half will slant the other. We’ll walk through that in the next step.

Finished May BOM Block Using Half-Rectangle Triangles

Here’s a look at my finished May block, using the trimmed HRTs we just made. The points are sharp, the seams are clean, and everything fits together beautifully. This block is a perfect example of how mastering one trimming technique can elevate your entire quilt.

For even more help, make sure to check out the full YouTube tutorial where I walk through every step. You’ll also find pressing directions and layout tips in your Block of the Month pattern.

Final Thoughts

Half-Rectangle Triangles can feel intimidating at first, but once you get the hang of trimming them correctly, they become a powerful tool in your quilting toolbox. Whether you’re sewing along with us for the 2025 BOM Party or adding HRTs to your own designs, this method will help you get accurate results every time.

Looking for more? Check out an older post: 2 Things You Need To Know About Making HRTs

Happy trimming—and happy May!