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Half-Square vs. Quarter-Square Triangles
Toby LischkoDescription
Half-square triangles and quarter-square triangles are both commonly used triangles in many quilt patterns and designs. Toby Lischko explains what the difference is between the two, how they are cut, and where they should be used.
Half-Square Triangles
A half-square triangle, which is commonly abbreviated HST in most quilt patterns, is a triangle that was cut from a square. Traditionally one will start with a square of fabric the size specified in the pattern, and then cut it in half diagonally once to get two half-square triangles. HSTs can also be made in other ways, including making half-square triangles with jelly rolls. HSTs can be used in several different ways. One way they are commonly used is in units that make up a block, which is taught in this tutorial on half-square triangle piecing.
Another way half-square triangles are used is in a quilt design that is set on point. Because an HST is made from cutting a square in half, two sides of the triangle will have straight of grain sides and one will have a bias edge. The HST can be used in the corners of an on-point design to ensure that the outer edges of an on-point quilt will have straight of grain edges.
Quarter-Square Triangles
Quarter-square triangles, which are common abbreviated QST in most quilt patterns, are triangles that were again cut from a starting square. You will begin with a square of fabric the size specified in the pattern and then cut it in half diagonally twice to get four quarter-square triangles. QSTs are commonly used in units that make up blocks and also in on-point quilt layouts as well. Because of the way they are cut, they have two bias edges and one straight edge. Using a QST as a setting triangle on an on-point layout will again ensure that all of the outer edges of the quilt will be straight of grain edges.
Many quilters use half square triangles and quarter square triangles in their quilts. But I don't know, as all quilters realize there's a special purpose for each one of these triangles. So let me talk a little bit about what half square triangles are and quarter square triangles are. And where they're used in quilts and quilt blocks. So, these are two squares that are cut on the straight of the grain. And what I'm gonna do is I'm gonna cut one into half square triangles. Half just means I'm gonna cut a square in half. Quarter square triangles means I'm gonna cut the square into four triangles. And I'm gonna show the difference between the two. So a half square triangle, make sure when you do that, you line up the edge of your ruler right on the center of that square on the corners, and you cut it in half. Keep your ruler nice and tight when you do that. So now I have two triangles that have two straight edges. Okay so two of these edges are on the straight of grain. So that's real important to remember. Now I'm gonna cut my bigger square into quarter square triangles. So, again, I'm gonna line up my ruler very carefully on the corner. On each of the corners. I want to be real careful not to move that square so I can cut in the other direction. Again, lining it up right along the corners. Okay, and now I have four triangles. Oh, this one got stuck a little. Okay, so now I have four triangles but you can see the straight of grain on these triangles is the long edge instead of the two corners that I have here. So there's a purpose for these triangles. When you're making a block, or a quilt, you have to make sure that the outside edge of your block, or your quilt, is on the straight of grain. Otherwise it'll stretch. The bias is very stretchy. So when you have the straight of grain on the outside of your edge, it doesn't stretch as much. So, when you're talking about half square triangles, they're gonna go on the corners of a quilt block. So here's an example. Of a corner of a quilt block. And I have these four triangles, and they're half square triangles because I want the straight of grain on the outside of this block, okay? Now here's a quilt that has quarter square triangles in it. And you can see here, this is my straight of grain. So these have to be quarter square triangles when they're on the inside of a block. So the rule is to remember, to help you remember is, quarter square triangles go on the inside of a block or the inside of a quilt, which are like setting triangles that you put in a quilt. And the half square triangles go on the outside edge of a quilt, or a block. So that you have the straight of grain on all edges of your quilt and your block.
Thank you for this video! I'm learning so much about HSTs and QSTs and how to use jelly roll strips in conjunction with them!
Would love the pattern for the star in the half square triangle description