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PAPER MATH

Since paper is routinely sold by the pound, it is useful to understand how the weight of paper is expressed.

Each grade of paper is available in certain Basis Weights. Offset Paper, for example, is available in Basis Weights of 40, 50, 60, 70, 80 and 100 Lb.

The Basis Weight is defined as the number of pounds that 500 sheets of a certain size weighs. That "certain size" is different for each grade of paper and is known as the Basis Size. The following chart shows the Basis Sizes for common Grades:

 
Grade Basis Size
Offset, Book 25 x 38
Tag, SBS 24 x 36
Cover 20 x 26
Bond (Sub Weight) 17 x 22
Index 25-1/2 x 30-1/2
Bristol 22-1/2 x 28-1/2

For example, imagine a pile of 500 sheets, 25 x 38, of Offset Paper in 60 Lb Basis Weight.


500 Sheets, 25 x 38, of 60# Offset

This pile would weigh 60 pounds. Accordingly, the weight of 1000 sheets (the "MWT") would be 120 pounds, 10,000 sheets would be 1200 pounds, and 123,456 sheets would weigh 14,815 pounds. Working backwards, you could calculate that 2000 pounds of 60# Offset in size 25 x 38 would constitute 16,666 sheets.

The sheet size required for a printing job often differs from the grade's Basis Size; however, once you know how much 1000 sheets in a particular size weighs, you can easily calculate the very useful Price per 1000 Sheets by multiplying the price per pound by the 1000-Sheet Weight, or MWT. The weight of 1000 sheets in a given sheet size is known as the MWT. In the example above, the MWT for 60# Offset in size 25 x 38 is 120M.

To calculate the MWT for any sheet size of a grade of paper, go to our MWT Calculator.

 
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