HST Tutorial

Time for another tutorial! Follow along these step by step instructions to guide you the next time you plan on making these ever so popular pieced squares.

I know many of you have made Half Square Triangles (or Right Square Triangles, Square Triangles, as well as a few other terms) in the past or you look to make some in the future. My hope is that this tutorial will guide you through the process many quilters might take for granted, but it's really worth the extra effort. I mean REALLY worth it.

About 98% of the time to make Half Square Triangles (from now on I will refer to them as HSTs), you start with two squares of the same size usually contrasting in color. You will line up these squares matching all edges with right sides together (I offset mine in the diagram to show you there are two "fabrics" involved in these steps).
 The next step varies depending on the technique you use to create your HSTs. There are many angling tools on the market now designed to specifically assist in this step (try a few out if you haven't already - BIG timesaver!) or many people will mark a line on the wrong side of the lighter fabric of the two to use as your guide. You pretty much have to choose one of these options to do, this is not something you can "eyeball" and be accurate at, sorry.
 Using either the angling tool or the drawn line as your guide, you need to stitch on both sides of the drawn line (or center of the block) with 1/4" seam. This is a great time to use a scant 1/4" seam allowance for a little extra wiggle room.

*Little side note: for the math behind HSTs, usually whatever size your block will finish at, you will cut the squares to be used making the HSTs 7/8" bigger. In all of my patterns and all quilts I make I always round up so my cut squares are 1" bigger than my finished HST. For example, in the pictures below my HSTs will finish at 2". Most patterns will tell you to cut the squares then 2 7/8", I however cut mine 3". The extra 1/8" doesn't sound like much, but we all sew distracted or tired or we're still learning at times and we're all human, mistakes happen. A little wiggle room makes all the difference some days, in the end I would rather have too much than not enough any day.
 Once both seams are sewn, cut the squares from corner to corner along the drawn line (or between the seams if you used an angling tool).
 Most HSTs are pressed to the darker fabric of the two, but for the pictures that follow, I pressed my seams open. Now that you've made HSTs, you're almost done, but not quite...follow along and I'll show you why.
 Remember that wiggle room I was mentioning earlier. This is where it needs to now disappear. Once you press your HSTs they might not all be square, or the right size. Notice the picture above, see all the overhang outside of the ruler and the 2 1/2" marks. It needs to go away. If you pieced your quilt with these slight extras on each block it could add up quickly and your quilt top or blocks will not be the right size and more headaches would follow.
 The trick for this step is to line up the square with the diagonal line on your ruler matching the seam. Whatever size your blocks may need to be, all fabric from the HST should be within that guideline.

*Some people have a hard time visualizing the correct size on their ruler. If you have a hard time trying to get the visual of the correct block size, put some tape on your ruler as guide lines. It's removable and won't damage your rulers for future use.
 Once you feel comfortable of the placement of the ruler, trim the two outer edges of the HST. I'm right handed so I trimmed the right side and the top, but do whatever feels more comfortable for you. A small spinning cutting mat is nice for this step too!
 Your HST should now look like this, two square edges and two uncut edges.
 Rotate the block 180 degrees so the two uncut edges are now "on the chopping block" hehehe (sorry been up since 4am, the coffee's finally kicking in! :] )
 Line up the two cut edges along the ruler marks for the size of your HST (remember these are finishing at 2" so they need to be trimmed to 2 1/2") and line up the diagonal line on your ruler against the seam. If you were accurate with your first two cuts, everything should line up perfectly here.
 Trim the final two sides and you should now have a perfectly square, perfect sized HST with the seam perfectly running from corner to corner, just how you want it to look.
By doing this you are assuring yourself of the accuracy of you piecing, you're removing all of the "dog ears" at the same time, and you get a little pile like this! This pile was the end result of "Squaring Up" or "True-ing Up" 508 HSTs for a little project I'm working on. I have found this is the only cutting step I can do while sitting down and my dining room table and office chair are the perfect heights to get the job done. I just pop in a movie on the laptop (usually something I've seen 100 thousand times but still love so I don't have to watch it, but can if I do so I can concentrate on my task at hand) and go. It took me about 3-4 times longer to press all 508 HSTs than it did to trim them, so it's not a really time consuming process.

I hope you learned something from this tutorial and will pass it along to others. I've been making quilts now for over 8 years and no one told me about this step until about a year and a half ago. I was wondering why even though my piecing was accurate (or close to it!) why things were still "off" at times. Think about this - you've seen them, you love them - Edyta Sitar of Laundry Basket Quilts, Carrie Nelson of Miss Rosie's Quilt Co., Jo Morton - yes THE Jo Morton. The quilts they design are gorgeous and a bunch of them have eight gazillion and one HSTs in them. If every seam they had in some of those quilts were off by even say an 1/8", it'll add up with each seam you do. Keep adding and adding and adding and see how this one little step will save you later on? It does make a difference.

I promise to you if you're like me - I first heard about it and thought, no way, not doing it. Then I did, but the first time I hated trimming all of those pieces...until I put my trimmed pieces together. It changed my quilting life forever. And it will to yours to if you try it.

Keep in touch as I'm sure more tutorials will be in the near future. It's a really chilly weekend here in Ohio, it snowed for the first time yesterday (nothing stuck on the ground yet so I'm happy) but it's still cold and rainy so I'm thinking a nice pot of homemade soup will be in the near future. I have an awesome quick and easy recipe for broccoli cheese soup that is sure to please and I should be making that soon. I will post a tutorial on that too so come back soon!

If you have any questions on the tutorial above or anything else I've mentioned, e-mail me at rubybluequilts at gmail dot com. I'd love to hear what you think of this and what's going on in your neck of the woods!


  1. I always allow wiggle room as well. It makes it so much less stressful!!

  2. Thanks for sharing! This is also how I do my HST. I am all about extra wiggle roon & it does make it easier in the end.

  3. Well, I was just about ready to give up on pinwheels. I think I'll give them another try after reading this tip. Now the question is do I redo the gazillion pinwheels and HSTs I made a few months ago?

  4. I like your idea of the wiggle room sewing distracted and or tired is a fact so.... I, too, would rather trim than have to deal with a square too small!!!!!

  5. Clicked on your site from Pat Sloans....so glad I did! I have avoided half square triangles for almost 10 years. LOL. I recently bought one of the tools to help with this and lots of 5 inch fabric squares. Really enjoyed your tutorial and signed up for your newsletter. So much to explore...fabulous. Have a great day!


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