Glossary Terms for Triangle Cutting Chart
- diagonal layout, diagonal setting
- corner triangle
- side triangle
- finished size
First we have to understand what side and corner triangles are. The corner triangles, shown in black, are in the corners. Side triangles, shown in gray, are along the edges.
Cutting Triangles from Squares
This triangle cutting chart is based on cutting squares then sub-cutting the squares into triangles.
Cut the square twice diagonally for side triangles.
Cut the square once diagonally for corner triangles
Why Cut Triangles from Squares?
Squares are easy to cut. First, cut along the width of fabric. Next, sub-cut into squares. Finally, sub-cut the squares into 2 or 4 triangles. Cutting squares this way ensures the grain lines follow the outer edges of the quilt.
The picture below shows the grain lines for the side triangle cuts. These cuts put either the crosswise or lengthwise grain along the outside edges of the quilt.
NOTE: Another way to cut side and corner triangles is to cut strips and use a specialty ruler. This method is covered in the article, Using Rulers to Cut Setting and Corner Triangles (coming soon).
How to Use the Triangle Cutting Chart
Step 1 – First, find the finished block size in column 1.
Step 2 – Next, find the corresponding number in column 2. Cut squares to this size in inches. One square gives you 4 side triangles.
Step 3 – Finally, find the corresponding number in column 3. Cut 2 squares to this size in inches. One square gives you 2 corner triangles.
NOTE: When in doubt about what size to cut, always round UP just to be sure. You can always trim it down later.
If you prefer to do the math yourself, here are the formulas:
(Finished block size in inches x 1.414) + 1.25″
(Finished block size in inches / 1.414) + .875″
Article – Grain Lines in Quilting
Article – Quilt Blocks Set On-Point