Paper basics

BASIC CONCEPTS:

Ream
Stack of 500 sheets

Basis Size
Standard sheet size. It is different for different kinds of paper.

Most common Papers and their Basis Sizes:
• Bond = 17” X 22”
• Cover = 20” X 26”
• Tag (and all C1S and C2S covers) = 24” X 36”
• Book (Text, Offset) = 25” X 38” 

Basis Weight
A weight of 1 ream of paper cut to basis size.

For example, if 500 sheets of 20" X 26" Cover stock weighs  80 lbs, we have "80 lb. Cover". 

80 lb. Text is not the same as 80 lb. Cover.
To achieve the same bulk as 500 of 20" X 26" Covers we would need to have 500 of larger sized 25" X 38" Text sheets.
 

There is no straight relationship between paper caliper (sheet thickness) and its weight.
The pulp in some papers is tightly pressed, while in others quite loose - all depends on usage requirements and manufacturing standards.
For example, coated stock (gloss / dull / silk, etc.) is thinner and denser than the Uncoated one.

Parent Sheet (PARS) or Full Sheet size 

Larger sized sheet we buy from a paper supplier.

Press Sheet size 

A sheet that gets printed on. It can be the same as the parent sheet, or we may cut the parent sheets down to a smaller size.
Typical scenario: buy 25" X 38" sheets and cut them 4-out to 12.5" X 19" press sheets.
 

M weight

Knowing only the weight of the ream of standard (basis) paper size will not help us to quickly find out how much would a specific amount of a different sheet size weigh.
For example, we bought 5,000 sheets of 28" X 40" 80# Cover stock. Can we put it all on one skid rated to hold 1,200 lbs.?


“M weight” helps us to figure this out. It gets calculated based on the following known factors:
 

So, 1,000 sheets of 28" X 40" 80# Cover would weigh 345 lbs.

If we have 5,000 sheets on the shop floor, that means: (5,000 / 1,000) X 345M = 1,725 lbs

And, here is a reverse formula - to find out the Basis weight if M weight is known

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There are 2 different ways a paper can be priced in North America:

Price “Per M” sheets

A price per 1,000 sheets (not a million! We use roman numerals here).

Because our sheets come in all kinds of sizes, every size would have a different price.

For example, 1,000 sheets of 23" X 35" 80# Cover would cost $600, while a 1,000 sheets of 26" X 40" 80# Cover would cost $800.

Price “Per CWT” - "per 100 weight" - "per 100 lbs"

A price per 100 lbs. of paper. Because we are not tied to a specific sheet size - just the weight - our 80# Cover will have the same "cwt" price, regardless of the sheet size.

This makes maintaining and adjusting the price lists much easier. So, most offset production sheet paper is bought by weight most of the time, but not exclusively.

Here are a couple of useful formulas to transfer back and forth:

Price per M sheets = Price per CWT * (M weight / 100)

Price per CWT = Price per M sheets * (100 / M weight)

An example of a typical suppliers’ catalog, showing the different prices per 1,000 sheets based on different sheet sizes and a common price "per cwt" (or per 100 lbs):

1980 Festival Plaza Drive, Suite 300, Las Vegas, NV 89135-2930

1-702-745-6967