Paper weight...huh?
There are two methods for describing the weight of paper. The first and easiest one to understand is gsm (grams per square metre). It is a simple calculation of the weight of a sheet if it were a square metre.
The second method is more complicated because it uses two descriptions to describe paper weight – a measurement of weight in pounds and term that describes the paper type. You will often see this method in North America.
There are four paper types and each has a standard paper size – Bond, Text (or Book), Index, Bristol, and Cover (or Card), although the first two and last are the common ones you will most likely run into. Numbers on printer/copy paper are based on Bond but may not reference this.
The following are the standard paper size for each:
| Bond | 17" x 22" |
| Text | 25.5" x 38" |
| Index | 25.5" x 30.5" |
| Bristol | 22.5" x 28.5" |
| Cover | 20" x 26" |
The weight is derived
from 500 sheets of the standard paper size.
For example, for 80# Text, 500 sheets that are 25.5” x 38” would weight
80#. So, this is where it can get
confusing, the paper size doesn’t have to match the standard paper size, so the
weight of the paper only represents if it did.
The second confusing factor is that 100# Text isn’t the same thickness
of 100# Cover. In this last example, the
100# Cover is about 80% thicker than the 100# Text.
Coincidently, a Ream
of paper is 500 sheets of the same size.
Here is a comparison chart of common paper weights:
| 20# Bond | 75gsm |
| 70# Text | 73gsm |
| 80# Text | 116gsm |
| 100# Text | 145gsm |
| 65# Cover | 175gsm |
| 80# Cover | 216gsm |
| 100# Cover | 270gsm |
| 130# Cover | 352gsm |
| 150# Cover | 406gsm |