8.5x11 for plotting...well, to get ideas down on paper. Actual plotting now is done in OneNote that came with my Office Suite. I used to write in a notebook, transfer it to Word, then from there, in Word, do an outline. As I'm writing the book, I use a copy of the outline because I inevitably switch things around, move plot points to different chapters. This helps me for when I go back and write a synopsis.