Half Square Triangle Charts and Beginner Tutorials

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Half Square Triangles are a foundational quilting block. This simple triangle block has so much potential. On its own, it may not look like much. But when you put several together, the impact becomes clear!

Because of its versatility, it’s used a lot.

Like a lot, a lot.

In fact, the Half Square Triangle may be the most common quilt block in quilting! It’s a big deal. And because it’s a big deal, it’s important to learn how to make it. Luckily it’s super easy and a great quilting block for a beginner quilter to learn.

There are several different methods for making Half Square Triangles. Because it’s such a common block, time-saving methods have been developed to make several at one time. Let’s face it, they can be time-consuming to make so it’s nice to be able to speed up the process!

This post will review how to make Half Square Triangles two at a time, four at a time, and eight at a time, and give you some helpful tips along the way.

Two at a Time Half Square Triangle Chart

This chart will show you what size starting squares you need to make your desired Half Square Triangle (HST) size. Quickly, let’s go through what each column means.

The Finished Size means the size your HST will be after it’s sewn into your quilt. This size does not account for the ¼” seam allowances all around the block.

The Unfinished Size means the size of your HST block before it’s sewn into your quilt. This size includes the ¼” seam allowance all around the block. You will trim your block to this size.

The Starting Square Size means the size your fabric squares should be before you assemble the HST.

The Beginner’s Starting Square Size means the size your fabric squares should be before you assemble the HST if you want a little extra room for trimming. This is the size I use and it includes an extra ⅛” of fabric.

How to Make 2 at a Time Half Square Triangles

Two at a time Half Square Triangles are one of the most popular methods to make HSTs. It’s a straightforward and no-fuss way to make Half Square Triangles. Plus you can make two at once. It’s great!

I love this method because it’s easy to remember and works perfectly when working with precut fabric like charm packs or layer cakes.

Let’s go through each step to make Half Square Triangles 2 at a time.

Beginner Quilter Tip: Start with fabric that is 1” larger than your desired Half Square Triangle size. This will allow you some extra trimming room so you can get super accurate blocks. Plus it’s easier to cut and do the math than the ⅞” in the standard HST math formula. This is how I do my Half Square Triangles and why I added the extra “beginner’s size” column to the chart!

Step 1: Place 2 fabric squares right sides together and draw a diagonal line on the back of one square.

Step 2: Sew ¼” away from either side of the marked line.

Step 3: Cut along the center-marked line to get 2 identical Half Square Triangles. Press seams toward the dark fabric.

Helpful Tip: Pressing towards the dark fabric will help the fabric not show through the front of the quilt. This is less important if your fabric are similar hues, but this method works great if you are using contrasting colors.

Step 4: Trim your Half Square Triangles to size.

That’s it! Easy, huh? The process is pretty straightforward but as you get going you may notice a few Half Square Triangle pain points.

The first is that it’s time-consuming, and the second is that your Half Square Triangles are ending up less than perfect.

I’ll address each pain point and offer some tips and tools to help you out.

Tips for More Accurate Half Square Triangles

Making a Half Square Triangle is simple, but making an accurate Half Square Triangle is another story.

If you’ve made a few and noticed that they are wonky and misshapen, you’re not alone. With a few adjustments, your blocks will see major improvement.

Check out these tips for accurate Half Square Triangles.

1. Cut the Starting Squares Bigger

Start with a square that is 1” larger than your desired finished block size. The HST math equation calls for adding ⅞”, but honestly that’s just too fussy for me.

The great thing about Half Square Triangles is that you can make them bigger and then cut them to size. So why not take advantage?

This is the exact reason I added a “Beginner Size” column to my Half Square Triangle Chart. It’s just easier and this extra buffer allows for more accurate trimming.

2. Be Mindful When Pressing

There are two things to keep in mind when ironing. The first is to press, not push. It’s important to pick up the iron and place it on the seam rather than pushing it back and forth on the seam. Pushing back and forth warps your fabric and causes things to get wonky.

The next thing to keep in mind is to press the block completely flat. When pressing a block open, it can be easy to press folds into the fabric if you’re not fully opening the block as you press.

If you don’t press the fabric completely flat, then the block will come out smaller than intended. Fully open the block and make sure you’re pressing on the seam.

3. Try (or DIY) a Specialty Ruler

Specialty rulers exist to help solve the issue of time-consuming and inaccurate Half Square Triangles. My favorite brand is Bloc-Loc. If you want an easy way to speed up the process and improve accuracy, I highly recommend investing in one of these rulers.

Are you more of a DIY person? Check out my Beginner Quilting Tips video to see how you can make your own Bloc-Loc ruler out of a square quilting ruler and painter’s tape!

Tips to Make Half Square Triangles Faster

A huge pain point I hear (and experience) about making Half Square Triangles is that it’s time-consuming. I get it!

Nothing is more spooky than reading a quilt pattern and seeing it calls for 215 Half Square Triangles. Seriously nightmare-worthy! Luckily there are a few things you can do to help speed up the process.

1. Chain Piece

Chain piecing is a method of sewing where you continue sewing your pieces one after another in an assembly line, instead of cutting your thread after you sew each seam. Not only does this save thread, but it also saves time!

To chain piece, sew one Half Square Triangle seam. When you’re done, immediately feed the next HST block through. If you do this to all of your HSTs, then you’ll end up with one long strand of blocks. Don’t cut the connecting threads yet!

Feed the other side of your HST blocks through and finish sewing both seams on each block before you cut the connecting thread.

Check out my Beginner Quilting Tips video if you want a more visual tutorial.

2. Start with a Full Bobbin (or Bobbins)

Nothing is worse than getting halfway through chain piecing and realizing that your bobbin ran out 4 blocks ago. Start your project with a full bobbin and have a few full bobbins on deck so you don’t have to spend time winding a bobbin in the middle of your project!

If you need a place to store all of those bobbins, check out this bobbin storage container.

3. Use a Rotating Cutting Mat to Trim

A rotating cutting mat is perfect for trimming Half Square Triangles. You can trim one side and instead of having to pick up and rotate the block, you can simply rotate the mat to trim the other side. This speeds things up immensely! This is my favorite rotating cutting mat.

4. Use a 4 at a Time or 8 at a Time Method

If you’re able, try using the four at a time or eight at a time Half Square Triangle methods. Making more HSTs at once will make the largest impact on how fast you can make these blocks. I’ll go over each of these methods in the next section.

If you’re a visual learner, you can check out my YouTube video to learn how to make faster HSTs!

Four at a Time Half Square Triangle Chart

This chart will show you what size starting squares you need in order to make your desired Half Square Triangle (HST) size. Quickly, let’s go through what each column means.

The Finished Size means the size your HST will be after it’s sewn into your quilt. This size does not account for the ¼” seam allowances all around the block.

The Unfinished Size means the size of your HST block before it’s sewn into your quilt. This size includes the ¼” seam allowance all around the block. Trim your block to this size.

The Starting Square Size means the size your fabric squares should be before you assemble the HST. The equation for 4 at a time HSTs is a bit complex, so this number is rounded up to the nearest 1/4″.

The Beginner’s Starting Square Size means the size your fabric squares should be before you assemble the HST if you want a little extra room for trimming. This is the size I use and it includes an extra 1/4″ of fabric.

Want to try the calculation for yourself? Divide your unfinished square size by 0.64, then round up to the nearest 1/4″. Add an extra 1/4″ if you want some extra wiggle room.

For example, we want to make (4) 5″ HSTs. The unfinished HST size is 5.5″ (add in 1/2″ for the seam allowances). 5.5″ / 0.64 = 8.59. Round up to 8.75 to get the starting square size. Add 1/4″ to get 9″ if you want the extra trimming room.

How to Make 4 at a Time Half Square Triangles

Four at a time Half Square Triangles will help you speed up your block-making process. Why make two at a time when you can make four, right?

Here’s a step-by-step tutorial on how to make Half Square Triangles 4 at a time.

Step 1: Place 2 fabric squares right sides together. Sew around the perimeter of the squares using a ¼” seam allowance.

Step 2: Draw two diagonal lines corner to corner to create an X on the fabric.

Step 3: Cut along the marked lines to get 4 Half Square Triangles.

Helpful Tip: Four at a Time Half Square Triangles have bias edges, which means the fabric easily stretches. Be mindful of this when pressing your fabric. Lift the iron up and press it flatly down on the fabric rather than running it back and forth to help keep the shape of the fabric.

Step 4: Press the seams toward the darker fabric and trim to the desired size.

Now you have a total of 4 Half Square Triangles! This method is fast and easy and works well if you have to make Half Square Triangles in multiples of four.

Eight at a Time Half Square Triangle Chart

This chart will show you what size starting squares you need in order to make your desired Half Square Triangle (HST) size. Quickly, let’s go through what each column means.

The Finished Size means the size your HST will be after it’s sewn into your quilt. This size does not account for the ¼” seam allowances all around the block.

The Unfinished Size means the size of your HST block before it’s sewn into your quilt. This size includes the ¼” seam allowance all around the block. Trim your block to this size.

The Starting Square Size means the size your fabric squares should be before you assemble the HST.

The Beginner’s Starting Square Size means the size your fabric squares should be before you assemble the HST if you want a little extra room for trimming. This is the size I use and it includes an extra ⅛” of fabric.

How to Make 8 at a Time Half Square Triangles

Making eight Half Square Triangles at a time can feel like you’re quilting in expert mode. You can make a ton of blocks super fast. Did you know it’s called the “Magic 8” method? Let me show you why!

Step 1: Place 2 fabric squares right sides together and draw two diagonal lines corner to corner to create an X on the fabric.

Step 2: Sew ¼” away from both sides of each marked line.

Step 3: Draw two perpendicular lines to create a plus sign on the fabric.

Step 4: Cut along the diagonal and perpendicular lines to create 8 Half Square Triangles.

Step 5: Press the seams towards the dark fabric.

Step 6: Trim your Half Square Triangles to size using a rotary cutter and cutting mat.

Wow! The 8 at a time Method is a great technique to keep in your back pocket for when you need to make a bunch of HSTs. Maybe next time you see “Make 215 HSTs” in a quilt pattern you won’t shudder… maybe.

Now you have the foundational knowledge to make Half Square Triangles. Yay!

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