How to Measure 10 x15 Inch Art on Standard Bristol Paper
The standard and most affordable top-peformance bristol paper is the 14×17 inch Strathmore 500 pads. The standard live area for original American comics art is 10×5 inches. The best way of centering this is keeping a 1-inch margin on top and bottom; then a 2-inch margin on left and right:
You could also go flush left, keeping a 1-inch margin on top/bottom/left, giving a 3-inch margin on the right. Centering gives you equal left-and-right space for notes.
The most basic comic book page is divided in a grid made of halves, thirds and quarters:
This is the space between panels. The exact size doesn’t matter, long as it’s consistently wide enough to define panels. If you’re using an inch ruler, the easiest gutter to manage is 1/4 inch. Be sure to use half your gutter distance above/below (horizontal) and left/right (vertical) of your gride guides. Graphic enlarged 200% for clarity: