Half-Square Triangles: Make + Design with HSTs

on March 21 | in Sewing + Quilting Tips, Sewing Tutorials + Patterns | by | with 17 Comments

Melissa from a happy stitch loves to sew and to teach others how to sew! Learn all about Melissa in her introduction, and have fun with today’s tutorial. Melissa’s easy how-to for half-square triangles (or HSTs) will get your mind spinning with possibilities!

I love the combination of versatility and interesting, easy techniques and that is why I was crazy in love when I discovered half-square triangle making (or HSTs). Half-square triangles are surprisingly easy to make but look really difficult and that certifies them as the perfect project for bringing on that awesome sewist feeling.

As a self-taught crafty gal, I really appreciate when things work in a way that is intuitive but also creatively challenging. As an aside that sometimes means I don’t really bother with proper titles and such… I mostly go for it. So, if there are technical terms for things I am doing and I neglect to mention them please do let me know. I love to learn more!

Here is how to make these fantastic HSTs.

Supplies you will need:

  • Two squares of fabric– one printed and one solid– cut at 7″ X 7″ (Or any size, really… Just know that your HSTs will end up being 65% the size of your original cut squares.)
  • Standard sewing supplies including a clear ruler, rotary cutter and self-healing mat

1. Place the two squares right sides together and sew around all four edges as below:

2. Use a clear ruler and set it across the middle of the sewn square. Be sure to position the ruler such that you will be cutting through the point where your stitches meet at each opposing corner. Once you have the ruler lined up, cut using a rotary cutter. Repeat across the other direction.

3. The result this will be four half-square triangles. all cut up into 4 triangles

4. When you press open each one and clip off the exposed seam allowances, it will look even more impressive. Nice, huh?!

Now, it’s possible to start making the triangles awesome!

1. This style is simple but elegant. With two on the top and two on the bottom sew each HST alongside each other with the print half of the square on the upper left-hand side. As simple as it is, this style can look so elegant repeated on a quilt.

2. To create a diamond, place each printed side of the fabric toward the middle.

3. To form a pinwheel, move clockwise from the top left placing each printed fabric on the right-hand side with just the tip of the print touching in the center.

4. This is a kind of flying goose style and is formed by placing two HSTs with the prints together and toward the center. Repeating the same for the bottom two.

5. I like to call this one the ‘egg timer’ but I have no idea if that is correct or not, I just made it up because that is what it looks like to me. Alternate each HST, moving counterclockwise with one print facing out and the next facing in toward the center repeating with the bottom two HSTs. Then rotate the whole thing to form a diamond.

6. Last but not least is the chevron. It is one of my favorites. Simply place two of the HSTs alongside each other with the prints together and then do the opposite for the other two HSTs below.

As far as sewing it all together, the trick is really to maintain a 3/8″ seam allowance. I will walk through how to sew the chevron but the same rules apply to sewing almost any HST. Begin by sewing, right-sides together, the top two pieces. Then do the same with the bottom two pieces.

Press open the seams and sew the top half to the bottom half. The best way to be sure everything lines up is to align the center seam of the both the top and bottom before you sew them together. Don’t worry so much about whether or not the edges are aligned… It’s always easy to cut away any any uneven edges without anyone knowing as long as the center is still aligned.

That’s it! So awesome and so easy! Now, if you made a bunch more of these it would form a zigzag.

Endless possibilities with the sturdy, tried and true, lovable little half-square triangle! If you want more inspiration, check out my Pinterest board… I filled it with fun options for HSTs! Go wild!

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17 Responses to Half-Square Triangles: Make + Design with HSTs

  1. amy jane says:

    Gahh! I love this! I’ve been wanting to make a quilt and this tutorial is awesome! I’m going to try the arrow design! Thanks… : )

  2. melissa q. says:

    I’m so thrilled that folks are finding this so useful!! I love it.

    I used a 3/8″ seam allowance when sewing around the edge of the two squares. As long as you are consistent when you sew, the HSTs should all end up the same. Sorry I neglected to mention that?! Whoops.

    Tina, I don’t know what to say. Perhaps, your seam allowance was a little off? Have you clipped off the bits of seam allowance that poke out after being pressed, that can help. And, don’t be afraid to square up your HSTs by cutting with a ruler and rotary cutter.

    Jim M, I do press open the seams to reduce bulk but you can do it either way. Yes, charm packs might be awfully small..unless that is what you are going for! I used a 7″ square for mine.

  3. tina says:

    I tried this way and have 4 squares that all measure different 🙁
    I followed exactly what u did…pic by pic…where did i go wrong?

    help pls

  4. Cheree says:

    This is the information I was looking for. Thanks and kisses!

  5. Vanessa says:

    I have a new pattern coming out and I had to make 300+ HST for the quilt and bedrunner samples. I used this method but I put to long strips together that were cut the correct width – in my case, 3 and 3/8″ (for 1.5 inch HSTs) and sewed down the two long sides of the strips . I then took the long strip that I had sewn and cut that into 3 3/8″ squares. I then chain stitched the squares on the two unsewn sides. This way I had a perfect 1/4 inch on all four sides. I then did the same diagonal cuts so that I ended up with 4 HSTs for each square. Thus, for two strips of fabric 3 3/8″ x 44″, I got over 40 HST

  6. Cherie says:

    What a great tutorial. Very easy to understand. Thank you!

  7. Bev Dickison says:

    I can not wait to try this!! Thanks

  8. Jim M in NC says:

    Thanks for the great tutorial. Definitely inspiring. I do have a few questions.

    The seam allowance here is 3/8″ not 1/4″? I caught that in the middle of the tutorial, when you initially mention sewing the two squares together I didn’t see a seam allowance mentioned.

    How well does this work for precuts? I would think pretty well for layer cakes but the using charm squares might get pretty small half-square triangles.

    Finally, you mentioned pressing OPEN the seams. I’ve always been told to press to the side. Is pressing open to remove bulk?

  9. Becky T says:

    I’m a fairly new quilter and this method is the only one I learned from Missouri Star Quilt Co. tutorials on YouTube. It works great and I’ve never had any troubles in my finished projects. I’m so glad you posted this because I have a layer cake just screaming to become a chevron quilt and I think I’ll tackle that this coming weekend!

  10. Beckyjopdx says:

    Is that a shot cotton? Super pretty! I have a heck of a time with the bias on this method so just do halfsies for now regardless of quality, but not as bad if I pin.

  11. Lissa says:

    You can also add 5/8″ to the finished size and with a 1/4″ seam it’ll come out right.

  12. Kate says:

    Thank you for this great tutorial! I’ve read of several ways to sew HST’s but found them all a bit intimidating. Your method makes me feel confident enough to give it a go! One question I have is what seam allowance do you use when you first sew around the square before cutting the triangles? I saw you mention a 3/8″ allowance later on when sewing the HST’s together but wasn’t sure if that was also the size you used in the first step. Thanks again, I can’t wait to get sewing some HSTs! 🙂

  13. Melanie says:

    Ok, yes! Thank you. I think I could have worked that out, but my geometry is rusty today. And every day.

  14. melissa q. says:

    Great questions! Yay Cyndy! Hi LIzzie, that is a great point about this method. It hasn’t given me much trouble but I haven’t tried this method with fussy fabrics. I’ve only used high-quality, tightly woven cottons…it might be harder with looser-weave fabrics.

    Melanie, sorry I wasn’t more clear..each individual half-square triangle is 65% of 7″ so this method creates 4 HSTs that are each 4.25″. That help?

  15. Melanie says:

    I’ve been using a different HST technique and LOVE that this makes four at a time instead of two. Thanks!

    So, the bottom chevron design is 65% of 7″ ? (Sorry, not so good at math here.)

  16. cyndy says:

    Wow! Thanks for this. I have layer cake I’ve been wondering what to do with…now I know!

  17. Lizzie says:

    I have seen this method before but haven’t tried it yet. I have heard people saying it can give you trouble because then you have 4 squares all with bias edges. Have you had problems with all the bias? Curious
    Because I’m making them 2 at a time and getting 4 squares instead of two would be really nice. Thanks for the tutorial. 🙂

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