How to make 2-at-a-time Half-Square Triangles + Math Cheat Sheet

2-at-a-Time Half-Square Triangle Tutorial: a step by step guide on how to make HST 2 at a time! This is a fun and easy way to quickly make a few HST in a pinch! See it in action in the video tutorial! #quilttutorial #halfsquaretriangles #diy

Are you ready to learn how to make 2-at-a-time half-square triangles?! There is a lot to love about Half Square Triangles.

Not only are they super cute! But they offer lots of versatility when it comes to quilting designs.

My quilt journey actually started with HSTs. I stumbled across a YouTube video on how to make them, and I was immediately curious. Now, quilting hadn’t even been on my radar. In fact, I had totally discounted it as something I would be interested in. Boy, was I ever wrong.

One HST led to another and another, and, before I knew it, I was well on my way to stitching my very first quilt top. That was back in 2015, and I’ve made a whole heck of a lot of half-square triangles since then.

Today I wanted to start you off with the basics of half-square triangles, or HST as they’re lovingly known in the quilty world 😊and what better way than starting with the super simple and very achievable 2-at-a-time method.

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WHAT YOU’LL NEED TO MAKE 2-AT-A-TIME HALF-SQUARE TRIANGLES

Before you can start creating your HST, you’ll need a few basic tools and materials to get started, including:

2 squares of different coloured fabric of equal size (more on sizing in a minute). I’m using prints from the *Sweetheart Bundle Up collection.
a marking tool – this is what I use, but a pencil or Hera marker would work equally well.
Some Pins (optional) – but if you’re just starting out, pinning reduces shifting, which leads to more accurate outcomes.
A Sewing machine – I sew on a Juki TL-2010Q and use a 2.0 stitch length when piecing.
Spool of thread for piecing – I stitch with 50wt Aurifil Thread in either white or cream.
A quilting ruler
A half square triangle ruler – optional
A rotary cutter
A cutting mat
A rotating cutting mat – optional but makes trimming super speedy! (You can read why I love it here!)
An iron
A wool pressing mat – use code SHANNONFRASER15 to save 15% on your small, medium, or large wool pressing mat at thefeltstore.ca or thefeltstore.com.
A tailor’s clapper – not required, but it can help get some nice flat seams.

With your notions at the ready, let’s dive into whipping these cuties up.

2-at-a-Time Half-Square Triangle Tutorial: a step by step guide on how to make HST 2 at a time! Here's an overview of the notions and materials you'll need to make your HST. #quilttutorial #halfsquaretriangles #diy

FABRIC MATH & HALF SQUARE TRIANGLE SIZES

What’s great about making 2 half-square triangles at a time is that the math required to figure out your starting square size is pretty straightforward.

A simple formula to follow is to add 1” to the finished size of your HST.

For example, if you want to make two 2.5” HST that finish at 2” when pieced, then your starting squares would be 3”.

The formula looks like this in action:

Desired finished HST size + 1” = starting square size

In this case, it would be 2” + 1” = 3”.

Easy, right?!

Here’s an easy cheat sheet I’ve created for you so you can quickly find the starting square size you need!

2-at-a-Time Half-Square Triangle Tutorial: a step by step guide on how to make HST 2 at a time! Here's a handy cheat sheet showing you the starting square size to make HST in sizes ranging from 1" through 10". #quilttutorial #quiltmath #halfsquaretriangles

HOW TO MAKE 2-AT-A-TIME HALF SQUARE TRIANGLES

The 2-at-a-time half-square triangle method is super handy if you just need to make 1 or 2 HSTs at a time. This was the first method I learned, and I didn’t realize there were other quicker methods – ha! So, several of the first quilts I ever made took me for-ever as I was making my HSTs only 2-at-a-time.

I don’t use this technique as often anymore, but it’s a great one to know if you need just a few HSTs in a pinch.

STEP 1

Start with 2 squares of fabric of the same size.

STEP 2

Draw a diagonal line from corner to corner on the back of one of your squares.

Place the squares right sides together (RST), making sure they’re lined up nicely.

Pin in place (optional).

2-at-a-Time Half-Square Triangle Tutorial: a step by step guide on how to make HST 2 at a time! Step 1 is all about size and Step 2 is marking! #quilttutorial #halfsquaretriangles #diy

STEP 3

Stitch a scant ¼” seam allowance on either side of your drawn line. (Unsure how to get a scant ¼” seam? I’ve got you covered in this tutorial.)

STEP 4

Cut on your drawn line. This creates 2 HSTs.

STEP 5

Set your seams by first placing the iron on your stitches before pressing your seams either to the side or open.

STEP 6

Trim your HST to your required finished size. See this tutorial for tips on squaring up your HSTs.

Now, step back and admire your perfect little half-square triangles!

SEE HOW TO MAKE 2-AT-A-TIME HALF-SQUARE TRIANGLES IN ACTION

See how to make your own half-square triangles using the 2-at-a-time method in this video tutorial.

Your turn!

Here are some quilt patterns featuring HST so you can put your newfound HST skills in action:

The real challenge after knowing how to make 2-at-a-time half-square triangles will be stopping at just making two!

Happy quilting!

Shannon

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