Disney Field Sizes
Calling something a Disney 12 Field would be very wrong. It would indicate a drawing area that is 28.88 inches wide! For proper conversion, see the converter boxes in the right sidebar!
You can find more info on the sizes used in some of the technical manuals I posted (much) earlier and on my separate page on this.
Suffice to say here that the ACME sizes refer to the width of the drawing area, so a 10 Field is 10 inches wide. The hight is then determined by the aspect ratio chosen. The Disney sizes were not calculated this way. An imaginary Disney 1 Field is 0 (zero) inches wide. They seem to in some way have been determined by the camera stand itself, at a very early stage.
[Addition: the paper size is, of course, somewhat larger than the drawing area it is named for, leaving some space on all sides, and room for the peg holes in the bottom (or top).]