Paper weight: What does it mean?
Paper weight can be confusing. There are two ways that paper weight is measured and stated. The United States measures paper weight in pounds, whereas it is standard to measure in grams per square meter outside of the US.
Paper weight in the US is stated in lbs. and is determined by weighing 500 sheets (a ream) in the basis size of a particular paper. For example, the basis size (or in other words, the master sheet size) of our Watercolor papers is 22”x30”. If you place 500 master sheets of our 400 Series Watercolor paper in the 22”x30” size on a scale, it should weigh approximately 140lbs.
The part that can get confusing when weighing paper in pounds is that not all paper types have the same basis size. For example, drawing papers have a basis size of 24”x36”, versus watercolor papers which have a basis size of 22”x30”. 500 Sheets of 400 Series Drawing paper (24”x 36”) weighs 80lbs. If you look at our 500 Series Aquarius II Watercolor paper, it also is listed as 80lbs, but the basis size of Aquarius II is 22”x30”, not 24”x36”, so it’s not exactly an apples-to-apples comparison.
On the other hand, weighing paper in grams per square meter does give you a clean, apples-to-apples comparison. Measuring paper weight in grams per square meter (commonly referred to as gsm or g/m2) is literally taking the weight in grams of 1 square meter of paper. So even though both Drawing and Aquarius II are listed as the same weight in pounds (80lbs), the master size sheets being weighed are not the same (again the drawing paper basis size is 24” x 36” and the watercolor paper basis size is 22” x 30”). When these two papers have the same size (one square meter), we see that the Watercolor paper actually weighs more than the drawing paper (130gsm vs. 170gsm).
COMMON PAPER WEIGHTS
This chart shows various papers and their common basis sizes & weights. A papers weight does not necessarily reflect quality. It is usually a reflection of intended use. Watercolor papers are heavier weight because of their need to hold a lot of water, versus drawing & sketch papers which are intended for dry media.
You will find the weight of our papers stated in both lbs. and gsm on our packaging, in our catalogs and on our website.