When we talk about paper weight, we think about two things. Either the actual weight of the paper or the thickness of the paper. And our papers are divided into those two weight categories:
Text stock: Measured in pounds (usually noted lb. or #), these papers are most often used for inside pages.
Cover stock: Measured in points (usually noted pt.), these papers are most often used for cover pages.
What does that mean?
Well for paper stock measured in pounds, also known as basis weight, it’s referring to the actual weight of 500 sheets of their parent sheets. Parent sheets are the sizes of the largest size sheet available for that type of paper. So let’s just say that a “Standard Sheet” of a particular paper is 25 x 38 inches for Text Stock and 20 x 26 inches for Cover Stock. And if you were to compare an 80# Text Stock to an 80# Cover Stock, you would notice that even though the “weights” are the same, the Cover stock is thicker.
When we use points for measurement, we’re referring to the actual thickness of the paper stock. And each point is equal to 0.001 inch. So a 10 pt. paper stock would be 0.010 inches thick and a 12 pt. paper stock would be 0.012 inches thick.
What about GSM?
If your printer was using GSM for measurements? What does that mean? GSM (Grams per Square Meter) is the metric equivalent of the point system. But Text stock isn’t measured in points…that’s correct and the conversion for GSM to Text stock and GSM to Cover stock are different. For Text stock it’s calculated by multiplying each pound of Text stock by 1.48. And for Cover stock it’s calculated by multiplying each pound of Cover stock by 2.708.
As an example:
80# of Text stock multiplied by 1.48 = 118.4 GSM
80# of Cover stock multiplied by 2.708 = 216.64 GSM
Common Text Stock # to GSM Conversion
50# X 1.48 = 74 GSM
60# X 1.48 = 88.8 GSM
70# X 1.48 = 103.6 GSM
80# X 1.48 = 118.4 GSM
100# X 1.48 = 148 GSM
Common Cover Stock # to GSM Conversion
60# X 2.708 = 162.48 GSM
65# X 2.708 = 176.02 GSM
70# X 2.708 = 189.56 GSM
80# X 2.708 = 216.64 GSM
100# X 2.708 = 270.8 GSM
Point to Approximate GSM Conversion
8 pt = 65# = 176 GSM
10 pt = 80# = 216 GSM
12 pt = 93# = 252 GSM
14 pt = 115# = 311 GSM
16 pt = 130# = 352 GSM