Scrappy Quilting Banner




How to Cut a Single Triangle


a square marked for cutting 2 triangles


single triangle after cut from square


Quilting triangles are usually made by cutting up squares. There are a couple reasons for this.  Usually you need two triangles, so there isn't any waste.  However the main reason is that  you want to avoid handling the bias as much as possible.


If you want a half square triangle, you cut a square once diagonally.  If you want a quarter square triangle, you cut the square diagonally twice. 

Half square triangles have the bias on the long side. 

Quarter square triangles have two bias edges on the short sides.


The following instructions are for making half square triangles.


The pictures below are of the Spool and Bobbin quilt square.  The Spool and Bobbin is a  4-patch quilt block that has been further divided into 16 patches.  As you can see from the picture, each block has 2 large squares in the corners that cover 4 of the smaller patches.


the spool and bobbin quilt square



The other 2 large squares contain the smaller patches.  There are some shortcut methods to make these blocks, but for the purpose of cutting triangles we are going to do it the long way.


Focus on the top left quadrant of the square.  You see a small square in the corner that has small triangles on each side of it, and a larger triangle on the bottom.  Here is how you calculate the measurements for these pieces and put them together.


Beginning with the small square, you can see that it fills just one of the smaller grids.  Planning each small grid to finish at 2 inches, these small squares are cut at 2 1/2 inches.  This is half of the measurement of the large yellow squares, which are cut at 4 1/2 inches.


To calculate the size of the large blue triangles, take the finished size of the large square, and add 7/8 inches.  Then cut it in half diagonally for 2 triangles.


To calculate the size of the small yellow triangles, take the finished size of the small square and add 7/8 of an inch.  Cut it in half diagonally for 2 triangles.


When you added 7/8 of an inch to the size of the square, 1/2 inch is for the seam allowances.  The additional 3/8 of an inch is for the seam between the triangles and the piece you will sew them to.


finished upper quadrant of spool and bobbin quilt block


Triangles cut for upper quadrant

Small sides attached to square and unit attached to large triangle


When attaching the small triangles to the square match the outer edges.  The pointed part of the the triangle will extend beyond the seam line.  Attach one triangle, press, and the do the other one.  Trim edges even as you go.


When attaching the top unit to the bottom triangle, keep the top unit facing up when sewing so that you can see when you get to the middle of the seam.  You want to sew right in front of the stitching line so that you do not cut off the point of the small triangle when it meets the large triangle.


You will not get into trouble cutting triangles as long as you remember the difference between raw and finished measurements, and use the 3/8 or 7/8 inch measurements.







Bear Claw Quilt Block

Quilt Sizes


Miniature      <36"
Wall Hanging any size

36x36 up to 52x52


52-68 x 52-78


64-72 x 86-96


70-88 x 88-100


88-99 x 94-108


94-108 x 94-108


Pre-cut Quilt Squares



Many beginning quilters like to buy quilt pre-cut quilt squares. While it is convenient, be aware you will need a lot of them. Here is approx how many 4-inch squares you need for the following size quilts without borders.


Crib 168
Twin 529
Double 624
Queen 728




Borders and Sashing
Pinning the Layers
Quilting Your Project



Resources for Frugal Living


Like Frugal Living?  Visit these Sites...


Eagle for

Squirrel for

Wood Stove for

Churn Dash Quilt block for

4 patch quilt block for


Be warm, be safe;  save time and money. 



Home      Privacy Statement