Originally Posted by maviskw

If you want an 8 inch finished block, the square will be 4 1/2 inches.
The small rectangle will be 4 1/2 X 5 1/2 inches.
The large rectangle to make the large triangles will be 8 1/2 X 9 1/2inches.

For a six inch finished block, the square will be 3 1/2 inches.
The small rectangle will be 3 1/2 X 4 1/2 inches.
The large rectangle to make the large triangles will be 6 1/2 X 7 1/2 inches.

A five inch block starts with a 3 inch square. etc. etc. etc.
You can figure that out no matter what size you want, but some are easier to figure out than others because dividing in half may yield strange measurements. For instance, if you want a 6 1/2 finished block, the square starts at 3 3/4. It's doable.

I hope I got this right!