Paper Weights Are Not What They Seem

Have you ever heard someone say that numbers don’t lie? Well, they do. Especially when it comes to describing the weight of a sheet of paper.

When our customers come in to compare papers they usually want to compare them based on pound weights like 20 lb. or 32 lb. or 60 lb. This is because here in America the pound weight is the most prominent number displayed on ream labels so it is also the most common number people use to compare how thick a paper is. But there is a fundamental flaw with this number.

The idea behind that 20 lb. value is that a 500 sheet ream of that paper weighs 20 pounds. So thicker papers should have a higher weight, right? Not necessarily.

In the photo below the package on the left contains 500 sheets of 70 lb. paper and the package on the right contains 250 sheets of 65 lb. card stock. So why are they almost the same height when one package contains twice as many sheets of a higher weight paper?

Comparison of paper packages

It’s because that 70 lb. rating is based on how much a 500 sheet ream of paper weighs in the basis (uncut) size. The paper in each of these packages has been cut down from a larger sheet of paper at the factory, but the label gives us no indication as to how those larger sheets compare to one another. In truth the 70 lb. weight refers to 500 sheets of 25×38″ paper and the 65 lb. weight refers to 500 sheets of 20×26″ paper. This makes comparing papers based on pound weight a fundamentally broken exercise.

But there is hope! Each label contains another number which looks a little more imposing but is actually much more friendly for the purpose of comparison. Below that 70 lb. notation on the label is a number which references grams per square meter also referred to as g/m2 or gsm. This describes how many grams each square meter of a sheet of paper weighs which is a legitimate direct comparison. Whether the cut sheet is 8.5×11″ or 11×17″ a square meter is still a square meter.

70 lb. paper label
63 lb. paper label

You will note in the above photos that my 70 lb. paper has a gsm value of 104 and my heavier 65 lb. card stock has a gsm value of 176. This measure is a true reflection of the paper weight as the 176gsm card stock is really heavier and thicker than the 104gsm paper. The pound weights would lead you to believe the reverse was true so let the gsm be your guide…

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