Half-square-triangle short-cuts and easy square-up

I have been making a LOT of half-square-triangle quilt blocks recently. Half-square-triangles (or HST’s) are one of the greatest basic building blocks of traditional quilting. I’m not a super-duper-precise piecer, but I am a firm believer in squaring-up blocks – especially half-square-triangle blocks. 
It just makes the piecing come together easier and look so much nicer in the end. 
But as we all know, the square-ing up process can get kind of tedious. Right? So I thought I’d share a trick I finally just discovered that has made the work SO much easier and faster. Oh my goodness, I don’t know why this took me so long to figure out. Many of you are probably already doing this, but just in case you’re like me, here’s the scoop:
First of all, this is my favorite basic method for making HST’s: Match two squares right-sides-together and draw a diagonal line down the back of one side. Sew a 1/4″ seam on both sides of the drawn line. Cut on the drawn line. This will create two HST blocks. I generally like to make my blocks slightly larger than the final size so that I can have room to square them up. If you are making a bunch at once – especially if you are chain-piecing them – it’s really easy for seams or matched-up squares to get slightly distorted. Here is the traditional way to square-up a half-square-triangle block.
This Quilt in a Day Square up Ruler makes the process SO MUCH faster. I’ve seen this ruler multiple times in shops, in my mom’s sewing room, etc. and always wondered what it did, but never bothered to find out. Well I finally did and it’s genius. The ruler is marked from one corner with traditional inchmarks divided into eigths. From the opposite corner it’s marked in half-inch lines.
Before you even open the HST block, lay the corner of the ruler on top of the pieced block and match up the marking for the desired finished size of the block, right on the seam. (So for example, I want a 3″ finished block, so I am laying the 3″ line on my seam, NOT the 3″ line on the bottom edge of the triangle.)
Trim two edges using a rotary cutter. By laying the mark on the seam you get a square block with the diagonal seam centered when you open up the block.
I then use my rotary cutter to trim off the ends so that I won’t have the little triangle tags when I open up the block. 
And voila – a perfectly squared-up 3″ HST block with no tags sticking out at the ends. Before you open up the block, press along the seam to “set the seam.” Then press the block from the front, careful not to pull or distort the diagonal seam, using the tip of the iron right on the seam to make sure it is fully opened and flat. Makes the blocks so nice and crisp and the best part is that I can get through a stack of them so much more quickly. I suggest doing the whole stack one step at a time. (For example: sew all blocks, trim all blocks, and then press all blocks, to streamline the process.)
I traditionally press my seams to the side – usually the dark. Sometime though I’ll press my seams open, especially if the blocks are small.
Here’s a repeat of the process again, this time making my block a 2 3/4″ block. Notice the arrow in the top left picture where I have lined up the 2 3/4″ markings with the seam. Trim two sides, open and press. (Ruler in bottom right photo only to show finished dimensions.)
I know there are a lot of quilty-gadgets out there, and you don’t need every one, but if you make a lot of HST’s and dislike the squaring-up part, Quilt in a Day Square up Ruler is worth it. (I know they are available also at JoAnn’s and from the Quilt in a Day site.) I now use it ALL the time.

If you’re looking for more half-square-triangle inspiration, here are a few other projects I’ve used them in: Half-Square-Triangle spectrum quilt,

this post contains affiliate links


  1. says

    It never entered my mind to square up hst before pressing! What a great tip; thank you. btw, I've been quilting 25 years, so that says a lot – always something new to learn.

  2. says

    I just picked up this ruler a couple of weeks ago. At Joann&#39;s–it was on clearance even! It&#39;s really cool! I have a pile of tiny crooked HSTs that I am now able to face :)<br />Thanks for walking us through the process!

  3. says

    Haha I have that ruler &amp; never used it. I remember picking up couple of years ago on sale &amp; saying &quot;I&#39;m sure this will work&quot; …..totatly forgot Thanks

  4. says

    That is an amazing set of quilts…and you make it look soooo easy! Thank you for sharing the process…you KNOW how I love processes!!! Happy Friday!

  5. says

    Great tool, thanks for sharing. Your spectrum quilt is what led me to your super informational blog. It&#39;s eye candy! I guess we all want to share our happiness in finding HST perfection bliss!

  6. says

    Oh, those specialty rulers in my sewing room are multiplying like bunny rabbits, and now you&#39;ve given me a new one for my shopping list! I absolutely adore your HST Spectrum quilt, by the way.

  7. says

    Love the ruler tip–I had not seen that before and turning a block 4 times (even with a turning cutting mat) is a pain. Also love that you can spell voila!! I can&#39;t stand seeing WA LA!!

    • says

      Haha! (I know right?!) Thanks. I&#39;m glad that taking 5 years of French has helped me in some small way. ūüėČ Because to be honest, I don&#39;t use it (or remember) much else.

  8. says

    It&#39;s funny… This week I also posted about how to make HST&#39;s using the Quilt in a Day ruler. It sure does make the process faster! Love your quilts.

  9. says

    This is a GREAT tut and I even own one of those rulers (but didn&#39;t know how to use it)! Thx so much! Being a newbie, it&#39;s great to learn all these neat tips! The whole squaring up a block thing is kinda mystifying to me as it is!

  10. says

    THANK YOU SO MUCH for this revelation! I&#39;m in process of construction of a quilt using over 200 HSTs and this tip has come in time to save me a lot of frustration!!!!

    • says

      Good question. I typically press to the side. (I&#39;m just traditional that way.) But occasionally I&#39;ll press open, depending on how intricate the block is (i.e. how many seams there are) or how small the triangle is.

      • Terry sHeldon says

        Machine quilters do tell me they don’t like pressed open seams…sort of ruins in-the-ditch quilting since there’s no fabric there.

  11. says

    I have this ruler and have always just used it as a square–duh…<br />This makes so much sense. I;m glad that you press to set the seam–so very few people do this and it is really critical.

    • says

      I ordered the 9.5&quot; version and it just arrived today. I&#39;m doing the Wishes QAL and it has lots of triangles. I&#39;m also doing the Vice Versa BOM and although I&#39;m not certain, I think there are some more triangles in my future there in the months to come, too!

  12. says

    Thank you so much! You saved my day with this post! I have been cutting squares for a quilt for my sister and need many HSTs which I hate squaring up! I am getting ready to sew now and I found your post. I thought to myself – WOW that is the ruler I have had laying in my drawer not knowing why I bought it or what to do with it… Now I know – and it will save me so much time and hassle! Yesss!

  13. says

    I went looking through my rulers and Yup I have an unused Quilt in a Day square up ruler. I am using it today and it is a much quicker way to square them up. We buy these rulers and then tuck them away. Thanks for the tutorial and for getting me to use it. .

  14. says

    Wow, I just bought that ruler on clearance at my local Joanns, it had been marked down to $7.95 then to $3.95 so I thought that even though I had never seen it used I had to get it for the price! Thanks for the explanation, it sure will make it faster to make those pesky triangle squares!

  15. says

    Thanks! I so needed this! I wondered how this worked! BTW, I first learned to quilt with your tutorial and made quilts for my great niece and nephew for Chirstmas! I have LOTS of HST&#39;s cut and sewn but, was really not liking this part. Now I&#39;m looking forward to getting back to it!

  16. says

    Thank you so much for sharing these tips!!! I have to make a lot of 1/2 square triangle blocks tonight and will dig out my Quilt in a Day ruler and give it a try!!!

  17. says

    So glad I came across your blog! Going to finish a project I started yrs ago with 2 inch squares. Needless to say I purchased the ruler. Unfortunately not at sale price. Oh well.

  18. says

    Thank you for this great way of trimming HST&#39;s. I love making them, but my back already aches when I think of the trimming process. Can&#39;t wait to try your method on my next ones.

  19. says

    I&#39;ve had one of these for several years and never used it. Occasionally I&#39;d pick it up and say &quot;hmmm&quot; and put it back. Thanks for your &quot;simple&quot; tutorial. I needed it!

  20. says

    I follow your directions and I made a quilt . it came out so nice. I wasn&#39;t on point on all the squares but it sure came out nice. thanks for the tutorial.

  21. Karen says

    Thank you! The ruler is now on my wish list. Your easier quilt patterns are an inspiration to a beginner, like myself! Your triangle quilt is fresh and inviting! Nice job!

  22. Susan Schoneweis says

    I’ve been looking for similar instructions for piecing hst’s using 16″ squares sown 4 times (I think) to make a bunch of hst’s at once. Learned it at a Saline county, Kansas extension program in 1985 called ‘painless Patchwork’. Lost the instructions. I’ve had my 16″ squares cut since 1986. Now maybe I’ll be able to get going again after finding your blog.

    • says

      Yes! So if you draw two diagonal lines on the back side of one of your squares (like an X) and do the same thing, sewing on both sides of the diagonal lines. Then cut the block into four 4″ squares and again on the diagonal lines, you’ll get 8 HST blocks from the two 16″ squares!

  23. Patty Dunn says

    I recently saw a die cut machine that cuts and squares up HST’s quickly and perfectly. I am curious if there are pro’s and con’s for doing the cutting this way? I don’t know anyone who uses one but am curious about them as it looks so easy? Thanks in advance for any input!

  24. Terry sHeldon says

    I have tried all the methode you can think of for HST’s, including this one, which works fine. But to me, the best way is using Thangles, which is what I always come back to. I have Thangles in every size they make. No worries about bias sewing due to the paper foundation, plus they come out perfect without having to square up. All you have to do is sew on the line!

  25. Rachel Provencher says

    OMG, this past weekend I made about 200 HST’s, and squaring them up is the part I dislike! Now I’m actually looking forward to the rest of them (all 600 of them). Thanks for a short, great tutorial.

  26. Cathy DiGuiseppi says

    I just found these instructions and they are exactly what I needed! I have had this ruler for years and never really knew how to use it! Thank you!!


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