I agree if you think you may run short don't do them diagonally but straight. A lot of quilters do it that way. I have done it both ways and they both work out fine.

I have used Edyta Sitar’s method cutting 1.75” strips successfully when short on fabric. if you watch the video you see you still have a double fold on the edges.
https://www.youtube.com/watch?v=jWauykQzr7w

Have you thought of the continuous bias binding method? It's a little tricky at first but 2 seams and a long cut, I use rectangles instead of squares. I figure how many square inches of binding I need and then measure the fabric. Sometimes I have a few to many seams in the binding but its the fabric I wanted and I don't really notice the seams unless one is dead center in the corner.

Book marked the calculator. That is clever and simple.

cashs mom thank you for the link to the binding calculator. And also there are so many suggestions and solutions here which I was not aware of. Will be following this thread.

I like that binding calculator. I can find out how much I need if I'm buying or juggle the width to find out how wide I can make it out of the fabric I have.