What are Half Square Triangles?
A Half Square Triangle (known commonly as HST), is a triangle that is half of a square. The long side is on the bias, and the short side on the straights of grain. If you remember your math, this would be the same as a "right square" triangle.
HSTs are a common block to use to create Friendship Star squares, Pin Wheel Squares, and many more. You can just start piecing them from all your scraps and make a very nice scrappy quilt. In it's most simple form, here is a HST square:
Making HST Squares
There are many methods for making HST squares. There are even templates and adhesive paper products for making them quick and fast. I will share my two favorite methods.
Perhaps the easisest way to make HST units is simply to take two squares, each 1/2" larger than your desired HST unit, and sew them together, as follows:
- Cut two squares of the same size, 1/2" larger than desired finished HST. (Many books recommend using a 3/8" extra, but I find that the 1/2" works better, and you have to square them up anyway.) For example, if you want a 5" finished HST, then you need to cut your two squares at 5 1/2" square.
- Draw a diagonal line, going corner to corner, on the back of the *lightest* square.
- Stitch a line 1/4" away from the diagonal line.
- Turn the square unit around and stitch a 1/4" seam on the other side of the diagonal line.
- Press the unit (to set the stitches) and cut the unit into two sections on the diagonal line.
- Open each square and press towards the dark fabric.
- Using a rotary ruler with a 45° angle, square up the units to your desired size.
The method above works fine when you only have to make a few HSTs, but what if you need 100 of these squares? Well, you can do a whole length of them at once.
- First, use the HST Calculator to determine how much fabric you need, and how wide to cut your strips: Start HST Calculator Applet
- You will need "cut strip width" size from the calculator. Let's assume your strip width is 5.25". Draw a perpindicular line every 5.25" on the wrong side of the lighter of the two fabrics.
- Next, draw a diagonal line, corner to corner, from each of the lines you just drew.
- Layer the second fabric on top of this right sides together.
- Stitch a seam 1/4" away on both sides of the diagonal line as illustrated.
- For ease of sewing follow the arrows as indicated on the illustration.
- Using rotary cutter and rotary ruler, cut the squares apart on each perpindicular line.
- Press each block to set the stitches, then cut on the diagonal line.
- Open each HST and press towards the darker.
- Trim all HSTs to the desired inch square.
Page last modified:
All graphics and content ©2001 QuiltPox.com & Kimberly Crapsey, unless otherwise noted. All rights reserved. That means, that any of the web graphics I created, or any of the text that I have typed, should not be used without my express written/verbal permission. You may not quote this web site in part or its entirety without first asking me. You may use any of the patterns herein for personal and/or commercial usage. Commercial usage is limited to 10 quilts/year. A referral to my web site is appreciated. Please email me before using patterns for educational purposes.