Four Half Square Triangles at a Time Plus Video

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Learn how to make four half square triangles at a time. They are super quick and are great for when you need a quick quilt top done!

This process is so quick and simple to do!! Once you figure out what size of squares you need- based on your finished quilt block size, you’ll be able to whip up half square triangles in no time!

There is a warning with this process. The outside edges of the half square triangles will be bias edges. That means that if you fiddle with them or stretch them when you press, move or sew them, you could run into issues.

*bias edges- be careful when pressing.


Half Square Triangle Cheat Sheet (found in the Quilters Resource Library- instructions for access at the bottom of the post)

Four Half Square Triangles at a Time Tutorial

1- Cut 2 pieces of fabric that are identical in size- square shape

2- Lay right sides together the fabric squares

3- Sew 1/4″ seam on all four sides of the square

4- Cut from corner to corner – repeat with other corner

5- Open the four half square triangles and press

6- Square up the quilt block- I use a bloc loc ruler (love it!)

You now have four half square triangles!


This quilters cheat sheet for making 4 at a time half square triangles using the math formulas below. 

You can either use the dimensions given or use the formula to figure out your own dimensions.

  • To figure out your own dimensions for making 4 half square triangles at a time you will need to know either the beginning square size you will be cutting or the size of the unfinished block you need.
  • Using the unfinished size half square triangle block you would like, for instance, 4 inches, you will take 4 and divide it by .64.  That will be the starting size square you will need to cut.
  • If you know the beginning size square you are starting with, say 6 inches, for example, you will multiply 6 x .64 and that will give you the unfinished size block that you will be making.
  • You can use the chart given below to find the correct measurements.  Some of these measurements are exact and leave very little room for error so I would add a little extra seam allowance or room to square up.
  • Try one set before cutting a whole bunch of squares. Make sure you have enough to trim for error or aren’t cut short.

You’ll find the four half square triangles cheat sheet in the Quilt Resource Library-

Four Half Square Triangles at a Time Video
Learn how to make four half square triangles at a time. They are super quick and are great for when you need a quick quilt top done! Watch the video!

Now that you have your four half square triangles all set, you’ll need to square them up.

This is a super important part of the process and not one that should be overlooked. There have been some pretty major quilt fails for me when I first started quilting- and it was all because I refused to square up my blocks. That was not fun and in fact those blocks are still haunting me! I really need to move them along to something else!

To help you not have as many issues as I did, here’s a quick video on how to square them up.

How to square up your half square triangles

Fun projects using half square triangles:

Half Square Triangles Download    Get the password for the library including this free pattern!

Half square triangle printable Download    Get the password for the library including this free pattern!


This resource library is open to everyone for free. All you need is the password to get in, which you can get by filling out the form below.

Already have the password? Access it here: Quilting Resource Library

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