394 Graphic Communications
Width of Basis
Length
×
sheets
×
weight
Length × Width of basic size
Example: What is the equivalent weight of a ream
of 28″ × 34″ ledger paper, 32-lb. stock?
28 × 34 × 32
17 × 22
To fi nd the total weight of a number of sheets,
use the following formula:
Weight of Number of
1000 sheets
×
sheets
1000
Example: What is the total weight of 1475 sheets of
17″ × 22″ – 56M, 28-lb. stock?
56 × 1475
1000
To fi nd the basis weight (when the sheet size and
ream weight are known) use the following formula:
Basic size × Ream weight
Length × Width of sheet
Example: What is the basis weight of a ream
of book paper 23″ × 29″, with a ream weight of
56 pounds?
25 × 38 × 56 53,200
23 × 29
=
667
The length and weight of paper in rolls can
be calculated by applying the factors shown in
Figure 21-16 to the appropriate formula.
To fi nd the length of paper in a roll of known width
and net weight (not including wrapper and core), use
the following formula:
41.67 × Roll weight × Factor
Roll width × Basis weight
Example: How many feet of paper are in a 1000-lb.
roll of 35″-wide offset book, 75-lb. stock?
41.67 × 1000 × 950
35 × 75
To fi nd the approximate weight of rolls on a 3″
inner diameter core, use the following formula:
(Roll Roll
diameter)2
× Width ×
factor*
= Approximate weight
*Roll factors:
Bond 0.021
Smooth Finish Offset 0.022
Vellum Finish Offset 0.018
C2S Web Offset 0.032
Example 1: What is the approximate weight of a
34 1/2″-wide, 40″-diameter roll of coated web paper?
(40 × 40) × 34.5 × 0.032 = 1766 lbs.
Example 2: What is the approximate weight of a
17 1/2″-wide, 40″-diameter roll of vellum offset?
(40 × 40) × 17.5 × 0.018 = 504 lbs.
Sometimes it is necessary to fi gure out how many
pieces of paper can be cut out of a large sheet. A
typical stock cutting sheet is shown in Figure 21-17.
To fi gure the number of pieces per sheet, the
dimensions of the desired cut piece are written
below the dimensions of the uncut sheet. First,
each dimension of the cut size is divided into its
corresponding full-sheet dimension. The resulting
whole numbers (fractions are dropped) are multiplied
to fi nd the number of pieces that can be cut from
the sheet. The computation is done two ways. In the
vertical method, the dimensions are divided vertically;
in the cross method, division is done diagonally.
An example of the two methods is shown in
Figure 21-18. Stock size is 25″ × 38″, while the
= Equivalent weight
= 81.4 lbs.
= Total weight
= 82.6 lbs.
= Basis weight
= 80 lbs.
Type
Business papers
Book papers
Cover papers
Printing bristols
Tag, news, conv.
Index bristols
Basic size
17″ × 22″
25″ × 38″
20″ × 26″
22 1/2″ × 28 1/2″
24″ × 36″
25 1/2″ × 30 1/2″
Factor
374
950
520
641
864
778
Paper Computation Factors
Figure 21-16. A factor is derived by multiplying the
dimensions of the basic size of a type of paper. For
example, the basic size of business papers (bond) is
17″ × 22″, which equals 371. (Inter-City Paper Co.)
= Length
= 15,080′