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I designed a ruler! The half rectangle triangle ruler + video tutorial


I have been waiting for this day for almost a year.  I designed a ruler for making half rectangle triangles last year while in the midst of the Bad Girl quilt along.  We were making all the HRTs with a paper template, do you remember?  So one day I sat down in Illustrator with a notebook and made ever line, every number, exactly what you see in the picture above.  It’s hard to believe that a file in my computer conjured up this tangible piece of acrylic.  Can you tell I’m excited?

I asked Havel’s Sewing to manufacturer it for me and they agreed.

Here we are a year later and I’m going to tell you all about how it works and a video tutorial so you can see it in action.

You can purchase this ruler right here.




There’s not that many HRT rulers on the market.  There’s some and I’ve tried them, but they weren’t giving me what I needed.

I want to make half rectangle triangles the same way I make half square triangles.  I want them easy breezy and two at a time, but HRTs and HSTs are two different beasts.  The most important aspect to me is that I DO NOT want to cut them in half and sew with a bias triangle.  I want all my points to line up after all and sewing on a bias (while sometimes needed) can make you crazy.

Enter the Half Rectangle Triangle Ruler.

With this ruler, you’ll start with two rectangles and make them similar to a half square triangle.  This ruler will let you trim your HRT in both directions.

You may remember this tutorial I posted last year.  The instructions on this ruler are the exact same as in my original tutorial.  The only difference is that instead of the paper template, we use the ruler.  I’ve created a video tutorial below to show you.

In the video tutorial below, I talk about the two different directions of HRTs and where to draw the line to get them in a certain directions.  I also show you how the ruler works and how to trim the two different directions.  Trimming is different depending on which direction you are trimming.




  1.  No matter what size you need, you’ll add 1″ to the unfinished size you want your HRTs to be.  For example if I want to make 3.5×4.5″ half rectangle triangles, my starting rectangles will be 4.5×5.5″.  This ruler will make sizes 2×4″, all the way up to 4.5×8.5″.
  2.  It’s important that you draw your line in the right direction.  Follow your pattern.  My patterns will tell you which direction to draw the line and you usually need some in each direction.
  3.  Two rectangles sewn together will give you 2 HRTs with the seam in the SAME direction.  So unlike half square triangles, you can’t make the mirror image from one set (see #2).
  4.  Sew a 1/4″ on both sides of the drawn line.
  5.  Cut directly on drawn line creating 2 HRTs.
  6. Press seams open and don’t forget to starch.
  7. Trim each HRT using the ruler.


Makes two at a time HRTs in both directions



I’ve got several new quilts designed that feature the half rectangle triangle shape that should come out this year.  Moon Goddess is first on my list and is just about to go into testing.  You’ll see the quilt reveal post up on the blog this coming Wednesday.

For now, the quilt patterns I have that feature a half rectangle triangle is the Bad Girl quilt and the I am Enough quilt.  I know, I know, I better get busy with some more!  I’m really wanting to make another Bad Girl though.  🙂




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  1. Congratulations Melanie! You are so smart! I watched the video and I can’t even imagine how you figured out how to make that ruler. So awesome!

  2. Congratulations Melanie. I think my first HRTs were in one of your quilt alongs and they were a disaster. Your video was great. Gonna get a ruler.

  3. Melanie, this is so cool! There really needed to be a ruler like this. Later this year I plan to run a quilt-along based on my HRT quilt called After the Rain. If you want to send me a ruler, I’d be happy to review it in the process of that QAL. Just a thought!

    1. The biggest difference between HSTs and HRTs is that if you draw or sew a 1/4” seam around a proper HST the stitching will line up right on the diagonal seam line. With this ruler your Diagonal seam ends up at the corners, but if you sew 1/4” around it you won’t end up on the diagonal seam line. How do you make your points match up in quilts when you need to use a different seam allowance to account for this?

      1. Is this in reference to Moon Goddess? If so, it goes into details about how to do that in the pattern. This way you don’t lose any points or corners. Let me know if I’ve misunderstood you. 🙂

        1. I am also curious about this- I love the idea of this ruler because I am working on a quilt with lots of HRTs (it’s not the moon goddess quilt), but I am not sure how I would make the points match up correctly using this ruler. Can you explain how to do this?

          1. Are you referring to the points of the triangle? If that’s what you mean, there is a video tutorial for turning them into diamonds in the Moon Goddess pattern. 🙂

  4. Hello! I’m learning to use the HST ruler for the Moon Goddess pattern. For the colored fabric, I picked a stripe (silly me) but after trimming the stripes came out wonky. Are there precautions I should take to make sure my stripes come out parallel to the edge of the rectangle? Thanks!

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