How to Make Half-Square Triangles (HSTs): 3 Easy Methods for Quilters
If you’re a new quilter, chances are you’ve run into half-square triangles (HSTs) already, and if you haven’t, you will soon! HSTs are one of the most versatile and beginner-friendly blocks in quilting. From pinwheels to chevrons, they show up in all sorts of classic and modern designs.
Today, I’m breaking down three simple methods to make half-square triangle units, along with formulas for choosing the right starting square sizes. Let’s stitch!
What is a Half-Square Triangle?
A half-square triangle is a square made up of two equal right-angle triangles, divided along the diagonal. They’re simple in construction but full of design possibilities.
Now let’s get into the good stuff, how to make them!
Method 1: Two at a Time (Quick & Simple)
This is the most common way to make HSTs, especially if you only need a few for your project.
How to:
Place two squares right sides together.
Draw a diagonal line from corner to corner.
Sew ¼" away from both sides of the line.
Cut along the drawn line to make two HSTs.
Press and trim to your desired unfinished size.
Formula:
Starting square size = Finished HST size + 1 inch
Example:
Want a 4" finished HST?
Start with two 5" squares (4 + 1 = 5)
Download the Half Square Triangle Cheat Sheet HERE!
Method 2: Four at a Time (No Marking Needed!)
If you want to speed things up a bit and avoid drawing lines, the four-at-a-time method is for you.
How to:
Place two fabric squares right sides together.
Sew ¼" around all four sides of the square.
Cut the sewn square diagonally in both directions (like an X).
Press open and trim as needed.
Formula:
Starting square size = Unfinished HST size ÷ 0.64
Then round up to the nearest ¼" for accuracy.
Example:
Want a 4-½" unfinished HST?
4.5 ÷ 0.64 = 7.03 → Round to 7-¼"
Start with two 7-¼" squares
Download the Half Square Triangle Cheat Sheet HERE!
Method 3: Eight at a Time (Batch Maker’s Favorite)
Need a lot of HSTs in a hurry? This method lets you make eight at once!
How to:
Place two squares right sides together.
Draw two diagonal lines from corner to corner, forming an X.
Sew ¼" on both sides of both diagonal lines.
Cut the square horizontally, vertically, and along both diagonals—you’ll end up with 8 triangles.
Press and trim.
Formula:
Starting square size = (Finished HST size × 2) + 2 inches
Example:
Want 3" finished HSTs?
(3 × 2) + 2 = 8
Start with two 8" squares
Final Thoughts
Each method has its place in your quilting toolbox. Use the 2-at-a-time for smaller projects, the 4-at-a-time when you want a fast, no-marking option, and the 8-at-a-time for those big quilts that call for dozens of HSTs.
No matter the method, a little extra trimming makes your blocks shine!
Have a favorite way to make your HSTs? I’d love to hear in the comments or over on Instagram @StraightStitchingQuilts.
Happy stitching, friends!
Download the Half Square Triangle Cheat Sheet HERE!
About the Author
Tiffany Bynum is the pattern designer behind Straight Stitching, creating beginner-friendly PDF quilt patterns rooted in traditional techniques. Her work has been featured in Love of Quilting magazine, and she has designed patterns featured with Art Gallery Fabrics and Hoffman California Fabrics. Additionally, she is a 2026 Maywood Makers participant.
