Definitions for "Basic Size"
Keywords:  ream, bristol, customary, grade, sheet
The basic size is that size from which the limits of size are derived by the application of allowances and tolerances.
Parent sheet size of a grade of paper. 25 x 38 for book papers 20 x 26 for cover papers 22 1/2 x 28 1/2 or 22 1/2 x 35 for bristols 25 1/2 x 30 1/2 for index.
The standard sheet size given to each type of paper that determines its basic weight.