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Shannon Fraser Designs

Spreading quilty joy one stitch at a time!

How to make 4-at-a-Time Half-Square Triangles + Math Cheat Sheet

April 12, 2022 by Shannon 8 Comments

How to make 4-at-a-time half-square triangles - this tutorial includes a math cheat sheet to make creating HSTs easy peasy for you! #shannonfraserdesigns #hst #halfsquaretriangles #quiltingtutorial

Today, I’m popping in to share some more practical tips and tutorials that I would have loved to know about when I first started quilting! Knowing how to make 4-at-a-time half-square triangles would have been a game-changer to learn early on.

As you know, half-square triangles (HST) is where my quilting journey started (you can see my first quilt here). I didn’t have a clue about chain piecing or nesting seams or even the need to trim your dog ears. Everything was new to me.

The only thing I knew was that I LOVED piecing, and seeing simple squares get turned into these fun HSTs that could then be used to create even more fun blocks was just the bee’s knees to me!

One of the first commissioned quilts I made was my Blue Odyssey quilt which was ALL about HST. It would have been so handy to know different methods for pulling so many HSTs together. But I didn’t at the time and made them with the trusty 2-at-a-time method I shared with you a few weeks ago. Knowing how to make several HST in one go is super handy so, today, I thought I would share with you the 4-at-a-time method with you 😊

4-at-a-time half-square triangle tutorial by Shannon Fraser Designs. This is such a great technique to have in your quilty tool box! I've even included a math cheat sheet to make creating HSTs easy peasy for you! See it in action up on the blog. #shannonfraserdesigns #hst #halfsquaretriangles #quiltingtutorial

*This post contains affiliate links, meaning, at no additional cost to you, if you click through and make a purchase, I may receive a commission.


MATERIALS & TOOLS

You don’t need any fancy tools to get started making half-square triangles – here are the essentials:

  • 2 squares of different coloured fabric of equal size (more on sizing in a minute).
  • A *Sewing machine – I sew on a Juki TL-2010Q and use a 2.0 stitch length when piecing.
  • Pins (optional) – but if you’re just starting out, pinning reduces shifting which leads to more accurate outcomes.
  • Thread for piecing – I stitch with 50wt Aurifil Thread in either *white or *cream.   
  • Quilting ruler*
  • Half square triangle ruler* – optional
  • Rotary cutter*
  • Cutting mat*
  • Rotating cutting mat* – optional but makes trimming super speedy! (You can read why I love it here!)
  • Iron*
  • Ironing board* or *wool mat
  • Tailor’s clapper* – not required, but it can help get some nice flat seams.

I typically stitch with a scant ¼” seam allowance (see my post here for tips on measuring that!)

Now that you’ve corralled your materials and tools, let’s get stitching!

4-at-a-time half-square triangle tutorial by Shannon Fraser Designs. This is such a great technique to have in your quilty tool box! I walk you through the materials you'll need right through trimming up your HST. I've even included a math cheat sheet to make creating HSTs easy peasy for you! See it in action up on the blog. #shannonfraserdesigns #hst #halfsquaretriangles #quiltingtutorial

FABRIC MATH & HALF SQUARE TRIANGLE SIZES FOR THE 4-AT-A-TIME HST METHOD

I’ve seen lots of different math formulas out there for the 4-at-a-time method. It seems no matter what technique you use, it all results in lots of weird decimal sizes for your starting square size.

To help keep this as simple and straightforward as possible for you, I’ve gone ahead and done the math for you and then rounded it up so that you’re working with more typical cutting sizes like ½” and ¼”.

In case you need to figure out a starting square for a finished HST that is larger than 10”, then here’s how that would play out.

The formula for 4-at-a-time half square triangles is to divide your unfinished HST by 0.64.

For example, say I want to make (4) 3” unfinished HST (they would finish at 2.5”), then the formula is: 3/0.64 = 4.6875

I like to round up, so that would make my starting square size 4.75”.

Note this calculation method doesn’t leave you with a ton of trimming wiggle room. So, if you want more room to trim your HST down, then I recommend increasing your starting square by a ¼”.

This calculation method is a little more complex, but you’ve got this!

STARTING SQUARE SIZING CHART

To help you in your HST journey, here’s a handy sizing chart in case you want to make ALL the different HST sizes 😉

4-at-a-time Half Square Triangle Math Cheat Sheet

HOW TO MAKE 4-AT-A-TIME HALF SQUARE TRIANGLES

STEP 1

Once you’ve identified the size of HSTs you want to make, the first step is to cut your squares. For each 4 HST, you will need 2 starting squares of the same size.

Here I’ve opted for floral and a low volume print

Place your two squares right sides together (RST) (i.e. good sides facing one another). Pop a pin in the center to help keep your squares from shifting on you.

STEP 2

Stitch a ¼” around the entire perimeter of the square. This is where knowing you’ve got an accurate ¼” SA is handy.

4-at-a-time half-square triangle tutorial by Shannon Fraser Designs. Step 1 and 2 is all about placement and stitching around the perimeter.  See it in action up on the blog. #shannonfraserdesigns #hst #halfsquaretriangles #quiltingtutorial

STEP 3, 4 & 5

Make two horizontal cuts, creating 4 individual HSTs.

4-at-a-time half-square triangle tutorial by Shannon Fraser Designs. Once you have them stitched, you need to cut the square on the diagonal. This is such a great technique to have in your quilty tool box! I've even included a math cheat sheet to make creating HSTs easy peasy for you! See it in action up on the blog. #shannonfraserdesigns #hst #halfsquaretriangles #quiltingtutorial
4-at-a-time half-square triangle tutorial by Shannon Fraser Designs. This is such a great technique to have in your quilty tool box! I've even included a math cheat sheet to make creating HSTs easy peasy for you! See it in action up on the blog. #shannonfraserdesigns #hst #halfsquaretriangles #quiltingtutorial
4-at-a-time half-square triangle tutorial by Shannon Fraser Designs. Love when you get to reveal the 4 HST you made in one go! This is such a great technique to have in your quilty tool box! I've even included a math cheat sheet to make creating HSTs easy peasy for you! See it in action up on the blog. #shannonfraserdesigns #hst #halfsquaretriangles #quiltingtutorial

STEP 6

First, set your seam by placing the iron on your stitches.

Then finger press the fabric back, making sure not to pull on the material, before pressing the seam flat with the iron.

To help your seams nest, you want to alternate pressing your seams to the dark and light side.

If you want your HSTs extra, extra flat, then consider using a *tailor’s clapper.

Trim your HST to your required size.

And you’re done!

How easy was that?

4-at-a-time half-square triangle tutorial by Shannon Fraser Designs. This is such a great technique to have in your quilty tool box! I've even included a math cheat sheet to make creating HSTs easy peasy for you! See it in action up on the blog. #shannonfraserdesigns #hst #halfsquaretriangles #quiltingtutorial
4-at-a-time half-square triangle tutorial by Shannon Fraser Designs. Love making quick work of my HST and this is such a great technique to have in your quilty tool box! I've even included a math cheat sheet to make creating HSTs easy peasy for you! See it in action up on the blog. #shannonfraserdesigns #hst #halfsquaretriangles #quiltingtutorial
4-at-a-time half-square triangle tutorial by Shannon Fraser Designs. Modern Aztec Table Runner featuring the HST I made for this tutorial! This is such a great technique to have in your quilty tool box! I've even included a math cheat sheet to make creating HSTs easy peasy for you! See it in action up on the blog. #shannonfraserdesigns #hst #halfsquaretriangles #quiltingtutorial
Pictured above is the Holiday Modern Aztec Table Runner I made with these HSTs – pattern available in the shop.

SEE HOW TO MAKE 4-AT-A-TIME HALF-SQUARE TRIANGLES IN ACTION

I know how helpful it can be to see a quilting technique in action, so I filmed this quick video tutorial for you!

The video also includes two ways to trim your HST using a regular ruler and this *specialty half-square triangle ruler.

Your turn!

Have fun stitching these up and creating adorable fabric combos. Just beware, they’re addictive – ha! Good thing you now know how to make 4-at-a-time half-square triangles!

For modern quilt patterns featuring half-square triangles, check out:

  • Harvest Falls Mini/ Pillow
  • Irish Vortex Quilt
  • Shattered Star Table Runner
  • Spring is in the Air Quilt
  • Winter Star Quilt

What’s your favourite way to piece HST?

Happy quilting!

xo

Shannon


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Filed Under: Quilting, Tutorials Tagged With: Half-Square Triangles

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Comments

  1. Connie says

    April 14, 2022 at 8:16 am

    You have the same starting square making both a 5″ and 6″ unfinished triangles.

    Reply
    • Shannon says

      April 14, 2022 at 8:25 am

      Thank you so much, Connie! Great catch! Updated 🙂

      Reply
  2. Marty says

    April 14, 2022 at 9:57 am

    Thank you Shannon, I love someone else, you have figured out the math!

    Reply
    • Shannon says

      April 14, 2022 at 10:20 am

      Ha! Marty, I’m happy to help out on the math front 🙂 It’s actually something I enjoy. Just remember that if you want trimming wiggle room, be sure to bump your starting square size by a 1/4″ inch or so!

      Reply
    • Shannon says

      May 5, 2022 at 2:16 pm

      Happy to help out, Marty 😘

      Reply
  3. Maryann West says

    November 6, 2023 at 12:07 am

    This entire article was a game changer for me. Incredible information has taken all the anxiety and fear out of HSTs. I am so very grateful. Thanks you!

    Reply
    • Shannon says

      November 6, 2023 at 6:43 am

      I’m so thrilled to hear the HST tutorial came in handy, Maryann! Have fun with this adorable block!

      Reply

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Hi! I'm Shannon. A modern quilt pattern designer based in Montreal. My quilting journey started by stumbling upon a half square triangle tutorial and I've been hooked since. I'm now spreading that quilty joy to you! Read More…

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