This half square triangle quilt post was updated in 2019 with additional information and video to make Half Square Triangle quilt blocks quickly and accurately.
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 ¼″ 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.
If you are making multiple identical Half Square Triangle blocks, in the video in this post I demonstrate how to make a large quantity all at once!
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 inch marks divided into eighths. 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 ¾″ block. Notice the arrow in the top left picture where I have lined up the 2 ¾″ 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,
Modern Gray and White Neutrals quilt
the Broken Dishes quilt tutorial
This Star Cake Quilt (free tutorial from the Fat Quarter Shop)
The Ganache spectrum quilt – pattern from It’s Sew Emma
Plus a whole pinboard of Half Square Triangle inspiration!
SUCH A CUTE QUILT!<br />THANKS FOR SHARING!<br /><br />email@example.com
WOW!! Amy I am going to have to find one of those rulers!! Thanks for the tip! I wonder if Joanne's carries this ruler, they have lots of other Quilt In a Day supplies.
Yep! I think I got mine at JoAnn's!
I took a class from Eleanor and have been using this ruler ever since. I've convinced others to buy this ruler also.
Nice tut! I love that spectrum quilt with the all over HST
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.
This is really neat, thanks for sharing. Now I have to look in my messy drawer for this ruler!!
Lucy @ Charm About You
Yes that is genius!!
I just picked up this ruler a couple of weeks ago. At Joann's–it was on clearance even! It'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!
Haha I have that ruler & never used it. I remember picking up couple of years ago on sale & saying "I'm sure this will work" …..totatly forgot Thanks
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!
I just purchased the Quilt in a day ruler on clearance. Perfect timing on the tutorial on how to use it. Thanks so much!
AWESOME! I love HSTs, but I get so bored having to square them up. I'm definitely getting this ruler in my next Amazon order! Thanks for posting this!
I loathe squaring up HSTs! I must buy this. Thank you for showing me the light! 🙂
This needs to be added to the bottom of all HST tutorials. Genius way of squaring up!
Another ruler on my wish list. Great blog and I agree with SeeMaryQuilt!
Paula @ Sewy Stuff
Definitely looks easy! "Gotta get me one!"
Great tool, thanks for sharing. Your spectrum quilt is what led me to your super informational blog. It's eye candy! I guess we all want to share our happiness in finding HST perfection bliss!
Brilliant idea. I've just ordered one.
B. J. Woodlee
Thanks for sharing. I've got to get three on order one for each of my two sisters and one for myself. Love your quilts.
Jenn @ A Quarter Inch from the Edge
Thanks for the tip on the ruler! I make a lot of HSTs and didn't know it existed! Happy Friday!
Oh, those specialty rulers in my sewing room are multiplying like bunny rabbits, and now you've given me a new one for my shopping list! I absolutely adore your HST Spectrum quilt, by the way.
This is brilliant! Thank you!
Brilliant! Heading to a quilt show next week and will definitely seek this out!
I am heading to Joanns tonight…. I hope they have one. <br />Thanks for sharing<br />Shawn
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't stand seeing WA LA!!
Haha! (I know right?!) Thanks. I'm glad that taking 5 years of French has helped me in some small way. 😉 Because to be honest, I don't use it (or remember) much else.
Terry@ a quilting blog
Your quilts are beautiful!!! I have that ruler and love it!
An even better tool is the BlocLoc ruler. It has a groove in the back to hug your seam – it is fabulous!
Susan Strong (strongstitches.wordpress.com)
That's genius! I've never seen that ruler before but will be asking for it at my LQS. And I have a HST project in mind to try it out. Thanks for the tip.
Thanks for the great tip! Now I can look forward to doing some half-square triangles.
HSTs are one of my favorite blocks. I was using the traditional method for squaring up, but this is pretty genius. Thanks for sharing Amy!!
It's funny… This week I also posted about how to make HST's using the Quilt in a Day ruler. It sure does make the process faster! Love your quilts.
I have a stack of triangles that I've been afraid to touch. This will definitely be helpful in making it as painless as possible!
Petit Design Co.
I too have seen the ruler and never bothered to figure out how to use it. Good thing tomorrow is Saturday and I have some Joann's coupons! Thanks for sharing
This is a GREAT tut and I even own one of those rulers (but didn't know how to use it)! Thx so much! Being a newbie, it's great to learn all these neat tips! The whole squaring up a block thing is kinda mystifying to me as it is!
thanks for the tips
THANK YOU SO MUCH for this revelation! I'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!!!!
I shall add this to my collection of HST tips, but really, one of these days I'm hoping the HST fairy will just show up here…
Glad to know about this ruler and method. I make a lot of HST too. Did you press to the side or open?
Good question. I typically press to the side. (I'm just traditional that way.) But occasionally I'll press open, depending on how intricate the block is (i.e. how many seams there are) or how small the triangle is.
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.
YOU ROCK<br />really!<br /><br />thank you
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.
Thanks for sharing this. I need one of those rulers!!
I did not know of this ruler, thanks for sharing!!
Have you ever tried or heard of HST on a roll? (the paper version of making HST's)
I've heard of them. I need to give them a try sometime. I know they help a lot with accuracy.
Thanks for the tip! HST's are so versatile… and making the process easier is always appreciated…
Wow! Okay, I need this! I've seen it before, but like you, never paid attention.
Brilliant idea. I just love it.
I'm just branching out into triangles – this is a smart tool!
I ordered the 9.5" version and it just arrived today. I'm doing the Wishes QAL and it has lots of triangles. I'm also doing the Vice Versa BOM and although I'm not certain, I think there are some more triangles in my future there in the months to come, too!
Great post! Thank you for this information. I do dislike the squaring up (and that's putting it nicely). I must get this ruler! 🙂
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!
I must get one of these today before I start my next project using HST's. Thanks for the tip and tutorial!
I would be one of those people that would do it the hard way forever so THANK YOU for sharing! <br />I will be getting one of these ASAP!
Sold…I just ordered myself one of these rulers! I love HST! Thank you for sharing!
Sold too. It sounds like a great tool to have. Thanks so much for filling us in.
Thank you so much for this tutorial! I need to get one of these rulers ASAP! 🙂
Awesome tip, thank you so much!!
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. .
ah.. tão lindo, ver você fazendo parece tão fácil… quando pra mim não é…
Great tips Amy! I saw Corey/LMS talking about this on Instagram within the past week. It's been brought to my attention twice. Now I've gotta try it!
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!
Thaks for share this tips. We are beginners and we need to know about this things. Congrats!!<br /> https://lesantoniesblog.blogspot.com.es
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's cut and sewn but, was really not liking this part. Now I'm looking forward to getting back to it!
Loving this Amy! Thanks so much for the tips. I'll be pinning and sharing. <br />~Heather
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!!!
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.
Thank you for this great way of trimming HST's. I love making them, but my back already aches when I think of the trimming process. Can't wait to try your method on my next ones.
I've had one of these for several years and never used it. Occasionally I'd pick it up and say "hmmm" and put it back. Thanks for your "simple" tutorial. I needed it!
I follow your directions and I made a quilt . it came out so nice. I wasn't on point on all the squares but it sure came out nice. thanks for the tutorial.
I'm so glad! Thank you so much for letting me know!
Christina Lane | The Sometimes Crafter
I need that ruler! 🙂
Thanks for this post! How have I never seen this ruler before!?! I immediately ordered one.
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!
Thank you! I’m so glad. Beginner patterns are still my favorite. 🙂
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.
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!
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!
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!
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.
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!!
A big thank you for your blog.Really looking forward to read more. Fantastic.
These quilts are amazing! I love creating squares from different scraps, it is such a great way to use up left over material. We have a great post where we featured our Squares to Triangle Quilting Tool, which really makes cutting squares and creating triangles super easy! Check it out and happy quilting! http://www.quiltingfocus.com/2015/04/squares-to-triangle-quilting-tool/
Thank you SO much for saving my quilting soul!!!! All I have to do now is buy one of those little rulers.
Love your quilts. I plan to look at your patterns. Do you sell wholesale?
I am just working on getting hard copy patterns professionally printed to sell wholesale. Let me know if there’s something you’re interested in.
Because my products are specific for making rapid fire HSTs, what would be your wholesale price for the Hour Glass quilt pattern?
I have a booth at the Austin Area Quilt Guild Show in Austin, Texas September 15-18, 2016 (~4000 to attend). I would like to provide this pattern for client purchase, and to demo how the hour glass block is made using my tools. I also need the time to make the quilt for part of my display wall at the event.
Your patterns are very nice. I look forward to your response and our future business relationship. Thanks so much.
Have a lovely quilting day,
Owner, Quilt-N-A-Flash, LLC
In the photos of the tut, the upper left shows that the line on the ruler was EXACTLY on your seam line. The bottom right photo shows a ruler over the trimmed, opened block, but I see that it is a bit shy in the bottom left corner of the block. Your alignment for trimming was spot-on so it seems to me that your square should have come out perfect. Do you know what caused this discrepancy? The seam looks fully opened.
I often have this problem, I make sure the alignment is exact before trimming and make sure the ruler doesn’t move while cutting, but often I end up with a less-than-perfect square.
Cindy A Culbertson
Amy, I purchased the 6.5 quilt in a day square up ruler from your link. I am experiencing the same problem as the lady above. I wanted my 2 HST to be 5.5 inches after squaring so I started with 6″ carefully squared blocks. I lined up the 5.5″ mark on my accurate 1/4″ seams and trimmed using the quilt in a day ruler, but each one was consistently about 1/8″ off most of the way around the block. I called the company and they said the directions are to make 4 HST at a time and or to make quarter square triangles. There are no instructions to make only two HST at a time and the instructions said you had to start with a 12″ to get my desired size. Your tutorial looks like you are able to use this tool to make two HST at a time, so I am a little confused. Do you have any tips that would correct what I am doing wrong? I did try adjusting where I put the line on the seam but is harder to get it even and it still came out somewhat off. I love your blog and quilts btw?
Hmm – without seeing what you’re doing, I don’t know what’s happening. I have a video where I show how I use the ruler – maybe that will help? https://www.diaryofaquilter.com/2017/12/half-square-triangles-short-cuts.html
love the colors and fabric you choose, wonderful quilt
Thank you so much for this, I need to see if I can locate on in England. x
Great instructions I am going to buy this ruler. Have you tried the new block lock rulers.. Very expensive so I have not purchased.
I found your site by accident (or one of my angels took pity on me). Your site is wonderful and has helped get me partially back in the loop (I’ve got a lot to catch up on). I’m coming back to quilting after a 50 year sabbatical and boy have things changed (I started when we cut patterns from grocery bags). One thing I’ve noticed is that most sites highlight important info with reds or greens and for us color blind folks that makes it hard to see. I’m wondering if there is an alternative – luckily I have friends who don’t mind reading it for me (they also have learned some new tricks by helping me). Thanks for your great site.
This was fantastic info for a new quilter!!! I’m working on a batik HST quilt and was really not looking forward to squaring up 315 blocks for it – this method will make it go so quickly!
Thanks s much for the tip on the half square triangle square up ruler. I found this the other day and immediately ordered one. It really does make hst’s more fun. Have really been enjoying your blog.
O MY GOSH! I’ve just started learning how to do things, and am now just barely brave enough to try to do a HST, and seeing this helps calm my nerves some. I’ll definitely have to buy one and try it this summer while I’m not working. Thanks again for sharing!
I love hst’s and I am a beginner quilter. How do I sew the hsts together once I am done making them? I am so very confused.
Once they’re pieced, you sew them together in rows just like you would regular squares. THis tutorial is one example of sewing rows of half square triangles together: https://www.diaryofaquilter.com/2015/01/broken-dishes-baby-quilt-tutorial.html
I adore the look of hst but for some reason I dislike them so much like my arch enemy. My mom purchased the block loc rulers for me and they are ok but not perfect if you dont loc in the ruler perfectly. I am going to purchase this ruler and see if I can get past my dislike for them! Thanks so much for all your great imput and patterns to try