Here is everything you need to know about HRTs — Half-Rectangle Triangles. They are like the more worldly older sister of the HST (half-square triangle) and are just a tad more advanced. In this post, you’ll find out some key information before you delve into making your own.

What is an HRT?

HRT stands for Half-Rectangle Triangle. If you’ve been quilting for any amount of time, you’ve probably come across HSTs (half square triangles). The HRT results in an elongated version of the HST. It’s a teeny bit trickier but the results are worth it! Here, you’ll find plenty of diagrams and photos, including some for left-handed sewists.

If you’re trying HRTs for the first time, take some scraps and try out a few before starting on your first project. It will help you understand how they come together, and you can work out any stumbling blocks before you cut into the “good stuff.” I know from experience…!


As you can see below, the ratio of width to length affects the angle of the diagonal. The longer your rectangle, the steeper your angle. If you’re into math, we call this the slope of a line.

The most commonly used ratio in quilting is 1:2, so in this post, we will walk through how to construct a 1:2 ratio HRT. In diagram below, you can see a variety of different sizes of 1:2 ratio HRTs. Notice that the slope of the diagonal is the same for all of them.


The initial rectangles are cut an additional 1″ in width and an additional 2″ in length to the finished (sewn) size of the final HRT. Below is a chart to make a variety of sizes. You’ll notice that the ratio (width:length) of these initial cut rectangles is also 1:2.





1″ x 2″ 2″ x 4″ 1-1/2″ x 2-1/2″
2″ x 4″ 3″ x 6″ 2-1/2″ x 4-1/2″
3″ x 6″ 4″ x 8″ 3-1/2″ x 6-1/2″
4″ x 8″ 5″ x 10″ 4-1/2″ x 8-1/2″
5″ x 10″ 6″ x 12″ 5-1/2″ x 10-1/2″
6″ x 12″ 7″ x 14″ 6-1/2″ x 12-1/2″
7″ x 14″ 8″ x 16″ 7-1/2″ x 14-1/2″
8″ x 16″ 9″ x 18″ 8-1/2″ x 16-1/2″
9″ x 18″ 10″ x 20″ 9-1/2″ x 18-1/2″
I am making 3″ x 6″ finished HRTs, so I have cut 4″ x 8″ rectangles to start:


We’ll be cutting from corner to corner to get our triangles. (That’s why we start with a 1:2 rectangle — so we end up with a 1:2 angle or slope, if you’re feeling mathy).
HRTs cannot be rotated to manipulate the direction of your diagonal (unlike HSTs). The direction of the diagonal cut when making HRT blocks is crucial.  If you’re using prints, this is especially important and irreversible!
For Set A, cut the diagonal from top left to bottom right (on the left in the image below).
For Set B, cut the diagonal from top right to bottom left (on the right in the image below).

Offset seam

After you make your diagonal cuts, pair up your fabrics. Place right sides of fabric together at a ¼” offset seam. You can mark a 1/4″ mark from the diagonal to help you get started. With some practice, you’ll be able to eyeball this.

Sew a ¼” seam allowance. Press the seam toward the darker fabric or alternatively, press seam open.


There are two options for trimming your HRTs to size: Using a regular ruler, or using a HRT Bloc Loc ruler set (affiliate link). Here’s what we’re aiming for when we trim:

The diagonal does not meet the corner! This ensure that when we sew our HRTs together, they come together at perfect points.

Regular quilting ruler

You’ll need to use a ruler that is larger than your trimmed block. My blocks will be trimmed to 3½” x 6½”, so I’m using a 6″ x 12″ ruler. On my ruler, I have identified the:

  • ¼” x ¼” intersection
  • 6¼” x 3¼” intersection

I marked them with a permanent marker, which can be wiped off later with some rubbing alcohol. I’ve also marked the 6-1/2″ and 3-1/2″ lines with tape so I can see them more easily.

Align these markings with the diagonal seam line. Ensure that the 3½” line at the bottom is on top of the fabric. Trim excess at right and top edges.

Rotate ruler and HRT unit. Again, align 6½” x 3½” line with cut edges of the block. Ensure that the ¼” intersections align with the diagonal seam line. Trim excess at right and top edges.

Left-hand sewists, this will be what trimming Set A will look like:

To trim Set B triangles, you will mark a different set of dots on a different corner of your ruler. 

Bloc Loc HRT ruler

I invested a set of HRT Bloc Loc rulers (affiliate link). There are two different rulers, one for Set A and one for Set B. If you’re going this route, you will need to press your seams to one side. 
Align the seam with the diagonal groove of the Bloc Loc. Ensure that the 3½” line is on top of the fabric. Trim excess at right and top edges.

Set A with HRT Bloc Loc Ruler, for left-handed sewists:

When your HRT units are well-contructed and trimmed correctly, they come together like a dream! See how they come together with perfect points?