Easy Half Square Triangles Tutorial (VIDEO!)

Half Square Triangles

The half square triangle. What a beautiful thing! You can make hundreds of different quilts using just the simple HST. 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.

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.

Check out this 3 minute video tutorial – make 8 half square triangles 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.


Below I will demonstrate three different ways of making half square triangles and will also highlight some modern quilt designers today who use this versatile block. *Just a quick disclaimer, after learning these simple HST techniques, you might be tempted to recreate some of the modern quilts you see below. Please contact the designer before doing that. If the designer is selling the pattern, as a courtesy, purchase the pattern before replicating the quilt. Copyrighting a quilt pattern is very difficult since it is such an old art form. So let’s play nice and share the quilty love 🙂 xo

Half-Square-Triangles

Three Different Half Square Triangle Techniques

The amount of HSTs you need will determine which of these three techniques you will want to use. Based on what the pattern dictates, sometimes even within the same quilt you can use all three techniques. The first, is The Basic, which will produce 2 blocks. The second, is The Quad because, well, for obvious reasons, it will produce 4 blocks. The third technique is the Octo-Awesome technique (if you haven’t guessed, these names are home-brewed), and it will produce, ahum, can you guess? 8 blocks.

  1. The Basic – 2: Fig. 1
    • 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 ¼” seam on both sides from the guideline.
    • Cut along the guideline, press the seam and trim the dog ears.
  2. The Quad – 4: Fig. 2
    • Layer one light and one dark square, right sides together.
    • Pin squares in place.
    • Sew a ¼” 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.
  3. The Octo-Awesome – 8: Fig. 3
    • 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.

Fig. 1

Half Square Triangle Tutorial

The Basic Math Shortcut

Add ⅞" to the finished size you want. The fraction ⅞" translates to 0.875.

Finished HST

Cut Squares

Finished HST

Cut Squares

1"

1 ⅞"

4"

4 ⅞"

1 ½"

2 ⅜"

4 ½"

5 ⅜"

2"

2 ⅞"

5

5 ⅞"

2 ½"

3 ⅜"

5 ½"

6 ⅜"

3"

3 ⅞"

6"

6 ⅞"

3 ½"

4 ⅜"

6 ½"

7 ⅜"


Fig. 2

Half Square Triangle Pattern

The Quad Math Shortcut

​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. If you need to be precise, trim the half square triangles once they are sewn and pressed. To figure out the math, divide the unfinished HST size by 0.64.

Unfinished HST

Cut Squares

Unfinished HST

Cut Squares

1"

1 ⅝"

4"

6 ¼"

1 ½"

2 ⅜"

4 ½"

7"

2"

3 ⅛”

5

7 ⅞"

2 ½"

4"

5 ½"

8 ⅝"

3"

4 ¾"

6"

9 ⅜"

3 ½"

5 ½"

6 ½"

10 ¼"


Fig. 3

Make 8 Half Square Triangles

The Octo-Awesome Math Shortcut

Add ⅞" to the finished size and double it.

Finished HST

Cut Squares

Finished HST

Cut Squares

1"

3 ¾"

4"

9 ¾"

1 ½"

4 ¾"

4 ½"

10 ¾"

2"

5 ¾"

5

11 ¾"

2 ½"

6 ¾"

5 ½"

12 ¾"

3"

7 ¾"

6"

13 ¾"

3 ½"

8 ¾"

6 ½"

14 ¾"


Suzy Quilts Original HST Quilts

Triangle Jitters Quilt

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 an aspiring quilt designer, or if you are unsure about your creative skills, limiting your colors and even more specifically limiting your fabric to just solid is a great way 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 Quilt

Nordic Triangles is a pattern currently for sale in my shop. This pattern uses the Octo-Awesome technique for creating the HSTs. Because of the intricate way these triangles are varied throughout the pattern, this quilt can look vastly different based on the colors and the amount of colors one choses to use.


Lake Michigan In Denim Quilt

My Lake Michigan in Denim Quilt was inspired by the denim quilts of Gee's Bend. This quilt is made up of more than 320 chambray, broadcloth cotton and Liberty of London Tana Lawn half square triangles. 


Little Girl Quilt

What's dreamier for sweet little naps than this purple HST quilt? 🙂


Quilt Designers Currently Producing Work

War-on-Bias-Quilt

War on Bias

Yara Greuter
Berlin, Germany​

In Yara's words:

War on Bias is semi improv. I usually work in illustrator but here I simply added on the design wall. 



This is the first quilt where I used materials that I had on hand – which was mostly old bedding and one vintage pillow (blue fabric) that we replaced. The blue fabric was kind of stretchy, which caused the name of the quilt. Since there was no way to get everything straight, I just went with it; it felt good to let go and just accept whatever form the quilt decided to take on. Thats also why I did not block it (honestly I never do…) and did not square it up in the end. I just trimmed off the batting. But the distortion is not very strong. In the pictures you can see everything is slightly off.



I used the 4 at a time method for the triangles which is tricky as you work on the bias. This also added to the wonk. I love working with HST as you can use them in numerous ways but I don’t like the trimming. I’m still on the lookout for a good rotating mat…Also I press my seams open whenever I can, but prefer the 2 at a time method as I generally don’t like to use starch.



I’m a big fan of negative space! I’m a trained swiss typographer which is influencing my work a lot. I like reduced color ways, black and white and generally prefer to work with solids. But I’m excited to see how living in Berlin will influence my work and how it will hopefully loosen up the strict Swiss in me!

Sunset Quilt

Sunset Quilt

Laura Preston
California, USA​

In Laura's words:

Like many, I’ve watched countless sunsets. There’s something really calming about watching the sun slowly dipping below the horizon, changing the sky around it into colors you didn’t think existed in nature. That a sunset is different every single day makes the event of witnessing this otherwise mundane rotation of the earth worth stopping what you’re doing to look at the sky.

Watching the sunset is universal. Everyone has watched the sun set and I would be shocked to find someone who doesn’t enjoy it. You know you’ve taken at least one photo of “the most beautiful sunset ever”.

I’ve watched the sun set in 39 states and I can’t say that any one place takes the cake for best sunset. They’re all incredible in their own way. Some dramatic and stormy, some technicolor, some gradual, but all fantastic.

The Sunset Quilt is a feeble attempt at capturing some of the vibrant colors that this daily event can produce. 

Maya Quilt

Maya Patchwork

Amanda Lanier
North Carolina, USA

The Maya Patchwork quilt was machine pieced with both new and repurposed cotton fabrics and was hand quilted using red cotton floss. All of Amanda's quilts are unique and have imperfections that make them beautiful and different.

Below is a HST cheat sheet so you can have all of the info in one JPG. Be sure to save it on Pinterest!

Half-Square-Triangle-Cheat-Sheet

Suzy Quilts

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15 thoughts on “Easy Half Square Triangles Tutorial (VIDEO!)

  1. RxQuilter says:

    Hi. The video says 5.5″ squares will yield 8 2.5″ hst is this correct? It doesn’t seem to match the table posed above for octo hst…maybe I am not understanding? Love this way and want to try!

    • Suzy says:

      No, you are totally right! 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. I’m so sorry for the confusion! I have added a note and I should have clarified that from the beginning. xoxo

  2. Melissa says:

    Thank you so much for this tutorial! It was so helpful and gave me enough encouragement at tackling a half triangle quilt.

  3. Shawna says:

    I love HST because of the flexibility to create several designs. Do you have a table that shows say I want to do a baby quilt or a lap size quilt and I already have a bunch of 6″ squares cut. How many squares do i need to make a proportional quilt? I have several 6 in squares and 10 in squares that I would like to do something with but I always struggle getting a proportional sized blanket so mine are always unique. haha. 😀 What is the typical size square you cut than can be used for several designs and sizes quilts?

    • Suzy says:

      I’m always change’n things up, so I can’t say that I cut a specific size of square to have for future quilting. If I were in your shoes, and had a bunch of 6″ squares, I’d probably pair the lights and the darks together and use The Basic HST technique. That way the blocks won’t get too small and they will all be proportional to each other. Thanks for the comment and happy sewing!! xo

  4. Amber Jordyn says:

    i ordered the Triangle Jitters pattern and after some head scratching I got to work. Just finished the quilt top today and I LOVE it. Am completely obsessed and already planning different fabric options. Thank you so much and I really enjoy your site. I am new to quilting and am gravitating towards a more modern look. You have given me so many great ideas and opened my imagination.

  5. Ashley says:

    You just made my week with this tutorial, and the technique breakdowns. I’m a total beginner but have wanted to figure out this type of triangle cut for so long…and then I found you! Thank you! I have a niece and a nephew due in a few months and I’m going to use them as my guinea pigs!

  6. Emma Carpenter says:

    Great info on hst and the varieties to cut; also appreciate the size charts for each method. Thank you.

  7. LindieLee says:

    Best sunset ever is in Albuquerque New Mexico. Have you been there? It’s like fire in the sky. All that fine dust from the desert kicking up into the atmosphere, I think, does something magical.

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