How To Make Half Square Triangles: Photo & Video Tutorials Using the 4-at-a-Time Method
- Heather Heck
- Jan 31
- 3 min read
Updated: 6 days ago
Video Tutorial Using the 4-At-A-Time HST Method
Start here if you prefer a video tutorial, or keep scrolling for a photo tutorial.
Watching the process can help clarify tricky steps and give you confidence to try out this method!
Photo Tutorial Using the 4-At-A-Time HST Method
Half square triangles (HSTs) are a fundamental building block in quilting. They are one of the first quilt blocks I learned how to make and I've used them in sooooo many patterns. There are lots of ways to make multiple HSTs at once with some of the most popular methods including making them 2-at-a-time, 4-at-a-time, and 8-at-a-time. Each method has it's place in different patterns and designs.
This quilting tutorial will guide you through the process step-by-step to make HSTs 4-at-a-time, making it easy to add this technique to your sewing toolkit.
Skip to the end for a step-by-step video tutorial if you prefer video learning!
Materials Needed
Before starting, gather the following materials:
Two squares of fabric the same size in contrasting colors
I want my HST to be trimmed to 2.5" and the finished HST size (after it's sewn into my project) to be 2".
Starting with a 4.25" square will allow for a little trimming room.
Starting with a 4" square will produce an HST that will be close to the exact size needed.
Rotary cutter and cutting mat
Quilting ruler
Half Square Triangle Ruler - optional (I like using this Bloc Loc ruler which is specifically used for trimming HSTs)
Sewing machine & thread
Iron and ironing board/mat
4-at-a-Time Half Square Triangle Starting Square Sizing Chart
Below is a handy chart that tells you what size of starting square to use, what size to trim to (unfinished size), and what size the finished HSTs will be (after they're sewn into your project).
Step-by-Step Guide to Making Half Square Triangles 4-at-a-Time
1. Gather Your Fabric Squares & Place Squares Right Sides Together
Start with two fabric squares of the same size. I want my HSTs to finish at 2". The chart above says I need to start with a 4" square. I wanted ample trimming room, so I added 0.25". My starting squares are 4.25" x 4.25".
Place the 2 fabric squares right sides together, aligning all edges carefully. Pin if needed to keep the layers from shifting.
2. Sew the Seam Lines
Sew a 1/4-inch seam around the entire perimeter of the square.
3. Cut the Square into Four Triangles
Align your quilting ruler diagonally from the top left corner to the bottom right corner. Use your rotary cutter to cut along the ruler. Without moving your fabric, adjust your ruler so that it is aligned with the top right corner and bottom left corner. Again, use your rotary cutter to cut along the ruler. You will end up with four smaller triangles.
4. Press the Seams and Trim the HST to Size
Open each triangle and press the seam toward the darker fabric. Alternatively, you can press your seam open.
Trim each half square triangle to the desired size. I'm trimming these HSTs to 2.5" x 2.5". I like using the Bloc Loc ruler, but you can use a regular quilting ruler to trim too. To trim, line up your ruler, so that the 2.5" lines are within the fabric and trim the top and right edges. Rotate your fabric square and align the freshly trimmed edges along the 2.5" lines on your ruler. Again, trim the top and right edges. This step ensures all your HSTs are uniform and ready to be sewn into your quilt.
5. HSTs are Ready to Use
That's it! All your HSTs are uniform and ready to be sewn into your project.
Final Thoughts on Making Half Square Triangles 4-at-a-Time
Mastering the 4-at-a-time half square triangle technique is a valuable skill for quilters and I hope you're able to put it to good use in your own projects!
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