Beginner and advanced quilty friends alike, I simply love that we all share one common thing — an appreciation for half square triangles! You can make hundreds of different quilts using just the simple HST. This half square triangles tutorial includes a conversion chart and instructions on how to make this wonderful quilt block three different ways. Oh! Plus a very early-days video tutorial I know you'll enjoy.
Comprised of simply a square made from two equal right triangles, this block is one of the most used and most versatile quilt blocks in history. Using the instructions below you will learn to make two at a time, four at a time, or eight at a time!
As a quilt designer, I find myself continually going back to half square triangles. It is a foundational block to some of the most famous quilts hanging in museums as well as simple baby quilts you find on Etsy. This quilt block is easy enough for beginners, but can be turned, rotated, resized and remade in so many ways, it remains complex and stimulating enough for advanced quilters.
Half Square Triangles Tutorial: Cheat Sheet
Half Square Triangles Video Tutorial: Make 8 HSTs at Once!
*Note: In the video I mention that a 5 ½" square makes 8 unfinished 2 ½" HSTs. Since then, I have changed the math so that there is a little more wiggle room in the sewing and cutting. According to the chart below (which I recommend using) a 5 ¾" square will produce 8 unfinished 2 ½" HSTs.
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Check out the HST conversion charts below for three different ways of making half square triangles! Bookmark this half square triangles tutorial so you can come back to it.
3 Different Half Square Triangle Techniques
The amount of HSTs you need and the size of fabric you are using will determine which of these three techniques you should choose. Based on what a quilt pattern dictates, sometimes even within the same quilt you can use all three techniques!
The Basic: 2-at-a-time half square triangles
I recommend using this basic 2-at-a-time HST method if you only need to make a small amount of HSTs OR if you are working with scraps or small cuts of fabric. I say this because this method allows you to use fabric this is only slightly larger than your finished HSTs.
- Cut two squares of contrasting fabric (we’ll say a light and a dark).
- Place right sides together and draw a guideline from corner to corner on the diagonal.
- Sew a 1/4" seam on both sides from the guideline.
- Cut along the guideline, press the seam and trim the dog ears.
2-at-a-time Half Square Triangle Conversion Chart
Add 7/8" to the finished size you want. The fraction 7/8" translates to 0.875. In all honesty, I hate weird little fractions like this, so I like to round up. For example, if I want a 6" finished HST, I'll cut my squares 7".
The Quad: 4-at-a-time half square triangles
This is a very popular way of making HSTs because it allows you to make your blocks in a large variety of fabrics while still being efficient. The one reason some quilters don't like this 4-at-a-time method is because once you trim your blocks all four sides are bias cuts. That means these blocks can be stretchy and easier to distort.
When using this method you can counteract the stretch by starching your fabric before cutting.
- Layer one light and one dark square, right sides together.
- Pin squares in place.
- Sew a 1/4" seam continually around the entire square, pivoting at the corners.
- Cut the square twice from corner to corner diagonally.
- Press the seams and trim the dog ears.
4-at-a-time Half Square Triangle Conversion Chart
This math is more complex and will sometimes end up with an odd decimal. The chart below rounds the decimal up to the nearest fraction. Trim the half square triangles once they are sewn and pressed. To figure out the math, divide the unfinished HST size by 0.64. (So for example, if you need a 3" finished HST, your unfinished HST will be 3 1/2".)
As I mentioned previously, I like to round when cutting. So for example, if I need a 6" unfinished HST, I'll cut either 9 1/4 or 9 1/2". Both would work since I will be trimming the HST down in the end no matter what.
The Octo-Awesome: 8-at-a-time half square triangles
This method is the fastest, however it does require the largest cuts of fabric. That may hinder you using precuts like fat quarters or layer cakes. If you were already planning on using yardage and just need a lot of HSTs in the same fabric, this is my recommended method. Just don't go so fast you cut off a finger. Been there, done that, and it ain't fun! 😉
- On your light square, draw two lines diagonally, one horizontally and one vertically.
- Place one light square on top of one dark square, right sides together. Sew a ¼” from the guidelines.
- Cut along guidelines.
- Press seams toward the dark fabric and trim dog ears.
The Octo-Awesome Math Shortcut
Add ⅞" to the finished size and double it. (Lately I've been rounding these measurements up to give myself some more wiggle room. You end up trimming all of your HSTs down afterwards, but your blocks are very accurate. eg. rather than cutting 5 ¾" squares to make 2" finished HSTs, I'll cut 6" squares. Make sense?)
Beginner-Friendly Half Square Triangle Patterns
If you're a new quilter looking to try out HSTs for the first time, start with these patterns! For patterns designed at a moderate difficulty level, keep reading.
Triangle Jitters is one of my first cracks at designing a quilt. As a newbie, and being very intimidated by the prospect of going off-book, I thought it would be best to limit my color palette. I also decided that sticking with one block would make the math portion of writing a quilt pattern much easier.
If you are interested in designing your own HST quilt, limiting the colors and even more specifically limiting the fabric to just solids are two great ways to ensure success. By simply rotating HSTs, I formed diamonds, lines and larger overall patterns. And by limiting the colors, this quilt is able to achieve a sleek, modern look.
Nordic Triangles is a classic for a good reason. This pattern uses the Octo-Awesome technique for creating the HSTs, so it's a very economical use of fabric. Because of the intricate way these triangles are varied throughout the pattern, this quilt can look vastly different based on the fabrics and amount of colors you choose. It also looks elegant in solids and fun in prints.
For the fat quarter-friendly version shown above, check out our ombré Nordic Triangles tutorial!
Summer Haze is a fun, scrappy, and fast quilt made entirely of HSTs and solid squares and rectangles. These simple shapes come together to make oversized diamonds that give the quilt its unique look!
Named after that haze late summer/early fall time, when sunsets are at the most beautiful and the leaves on the trees are just hinting at change, Summer Haze looks best with a wide variety of colors.
For even more tips on making HSTs, don't miss our three-part Summer Haze Tips & Tricks series!
The Rocksteady quilt pattern is the perfect example of how versitile half square triangles can be. This entire quilt is made using just one size of HST plus some solid squares!
If you're new to making half square triangles, this pattern is great for you because we have two excellent small tutorials to help build your HST confidence before jumping into the full-sized quilt. Our quilted Rocksteady table runner is a sophisticated addition to any home, and our Rocksteady Christmas stocking is one of the most popular Suzy Quilts tutorials ever!
Stars Hollow uses HSTs to create a fun combination of two quilt blocks — a Sawtooth Star and a Pinwheel. And in this pattern, you don't only get to practice your HSTs, you'll also make Flying Geese! Adding more blocks to your quilting tool box is particularly helpful for beginner quilters looking to grow into more advanced patterns.
If you are more of a neutrals fan, don't miss our tips for making a neutral Stars Hollow quilt!
Fly Away was one of my very first quilt patterns! If you're feeling bold, read the dramatic story of this design here, but be ready to ride a roller coaster of emotions.
HSTs are a classic but simple block. They're timeless. They can transform into new shapes, and playing with them can open new design doors. But sometimes, highlighting repeating HSTs can be both striking and soothing. These high-contrast HSTs, with tiny pops of color, are the perfect example.
And if you're looking for the perfect baby shower gift, try making a baby Fly Away quilt with a matching Fly Away bib!
Who doesn't love a mosaic? Found all over the world, mosaics are typically made from glass or tile. If you've ever wanted to snuggle up under a mosaic without being poked by hundreds of pieces of glass, this pattern is for you! There's even a video tutorial showing how to make the top and bottom triangle rows!
Moderate Skill Level Half Square Triangle Patterns
These patterns use HSTs in their construction, but also have more advanced piecing techniques. But don't worry, I'll walk you through what makes each of these patterns slightly more challenging!
Here's what I love about a pattern like Gather — it looks way harder than it is! This quilt has alternating HSTs at an angle that come to a point at the top, and that makes it seem like each HST has to be sewn on point. Nope! This quilt is made up of rows of HSTs and long strips of sashing fabric. That's it!
The hardest part of Gather is trimming. That's why Gather is listed as a moderate skill level pattern — it does have one hard part. I cover that and so much more in the Gather quilt sew along, including a video all about trimming!
The Voyage quilt gets its completely unique look by combining HSTs with a similar block — half rectangle triangles. HRTs are a little harder to make, so Voyage is listed as a moderately difficult pattern. Our seven-part Voyage quilt sew along that covers tips for HSTs and HRTs. After reading our sew along tips and making your first Voyage quilt, you'll be a pro at both blocks in no time!
New Horizons is a little more challenging for two reasons. First, the HSTs in this pattern have three colors instead of two. You'll be making your HSTs with strips of fabric pieced together! This adds another step to your HST process.
The other block used in New Horizons is called a stitch-and-flip block. So, like with Voyage, you'll be learning two new blocks in one pattern!
Holiday Party is made with HSTs, a template, and very precise cutting. That may sound intimidating, but we make it super easy in our Holiday Party quilt sew along!
For this quilt, we recommend making one full block before moving on and chain piecing each, especially if you are a beginner. That way, you'll be sure to understand each step of how the block comes together right away!
Ask Us Your Half Square Triangle Questions!
Do you have a question about making half square triangles? Or about one of our half square triangle patterns? Let us know in the comments and tell us which is your favorite technique in this half square triangles tutorial!