When you shop for paper online at The Paper Mill Store, you’ll notice that we also list a weight in addition to the paper mill and paper size.
The technical term for this weight is “basis weight”. There are many different types of paper, including cover paper, bond paper, and writing paper, and each has a different basis weight.
Basis Weight Explained
Basis weight, also known as paper grade or paper density, indicates the weight of one ream of paper, measured in pounds. One ream of paper consists of 500 sheets of paper. Simple, right?
Wrong. Picture a standard pack of 500 sheets of regular desktop printer paper (known by paper aficionados as “bond paper”). The packaging will probably say that it weighs somewhere around 20 lbs., but when you pick up the package, it certainly doesn’t weigh 20 lbs. This is because basis weight (the 20 lbs. labeled on the package) refers to the “basic size” of the paper you’re purchasing, not the size it’s been cut down to.
“Basic size” is the size of a sheet of paper before it’s cut down to the size that you purchase. And to make matters more complicated, basic size is different for every paper weight.
For example, the average sheet of letter size bond paper is 8.5” x 11”, but the basic size for the average letter size bond paper is actually 17” x 22” (basically, two sheets of letter size paper).
So the 20 lb. basis weight you see on your paper’s packaging actually refers to how much 500 sheets of the basic size, 17” x 22”, weighs, and not the weight of the letter size you purchase.
Weigh the Options
Only knowing what basis weight you need isn’t enough information to pick the perfect paper. 80 lb. text paper and 80 lb. cover paper are not the same thing (even though they have the same paper weight) because the text paper has a much larger basic size, which means each ream weighs more.
Make sure you know exactly what paper weight you need before you invest in a ream! Check out our infographic on picking the perfect paper before you make your final decision.
What the Heck is “Grammage Weight”?
Though paper is measured according to its basis weight in North America, most international countries use something called “grammage weight”. Why “grammage weight” specifically? Because these countries use the metric system, where weight is measured in varying degrees of grams.
Paper Size Matters
In order to fully understand grammage weight, it helps to understand international paper sizes. Most countries outside of North America use the “A4” system. A4 size paper is the closest international equivalent to our standard letter size paper.
This video does a fantastic job of explaining the difference between American and A4 paper sizing. Mind the bias.
- A0 paper is one square meter in area
- A1 paper is 1/2 of one square meter in area
- A2 paper is 1/4 of one square meter in area
- A3 paper is 1/8 of one square meter in area
- A4 paper, the closest equivalent to letter size paper, is 1/16 of one square meter in area
In order to understand grammage weight, you only need to concern yourself with the size of A0 paper – 1 square meter.
Grammage Weight Explained
Grammage weight measures the weight in grams of a single 1m2 sheet of paper. Unlike basis weight, grammage weight is not based on paper weight or basic sheet size.
Though The Paper Mill Store organizes its papers according to basis weight, you can find each paper’s grammage weight listed in each paper’s Specifications tab.