What Is the GSM Index?

Similar to choosing the right-sized mail piece, deciding its thickness can be just as tricky. While researching this, you’ve most likely encountered the GSM Index or GSM Conversion chart. GSM stands for “grams per square meter” and tells marketers and consumers the relative weight of the paper they’re about to order for their direct mail campaign. Internationally, GSM is the industry’s standard unit of measurement for comparing weights of different papers. 

GSM is based on the weight of a sample sheet cut into one square meter. The higher the value, the heavier the paper. For example, 263 gsm is much more dense than 52 gsm. 

Standard weight categories are as follows:

• 25 to approximately 60 gsm: This is the lightest paper stock, often compared to newspapers. 
• 74 to 90 gsm: This category is similar to notebook or notepad paper.
• 90 to 118 gsm: This is akin to household copy paper.
• 120 to 144 gsm: Many compare this to that of promotional posters. 
• 216 to 307 gsm: Thicker than the others, this type of paper is stiff but still bendable. 
• 315 to 488 gsm: The stiffest paper available, this category is mostly considered cardstock.

Although internationally GSM is the Industry standard, in the United States we use a system called Basis Weight. This measurement is expressed in terms of pounds. It’s based on the weight of 500 sheets (one ream) of the paper in its basic or parent size. Different weights and types of paper are manufactured in various sized sheets. 

The basic sheet sizes of each type of paper are:

• Bond: Also known as ledger or copy paper, the basic size is 17 x 22 inches.
• Cover Stock: This type is also commonly known as cardstock. The standard size for comparison is 20 x 26 inches. 
• Bristol: A heavyweight paper, this stock comes in a standard size of 22.5 x 28.5 inches. 
• Index: Similar to the thickness of an index card, the basic size is 25.5 x 30.5 inches.
• Tag: Based on a 24 x 36 inch standard, this is a thick stock.
• Text: A textured stock, the basic size is typically 25 x 38 inches.

When looking at purchasing paper manufactured internationally, or utilizing equipment that has GSM paper specifications, it becomes important to be able to compare the two systems.. Although the process is tricky, Design Distributors has done the legwork for our customers. The differing measures can be compared using a conversion formula. We’ve developed a GSM to Basis conversion chart to help compare the differences so you can make the optimal selection.

Download Our GSM to Basis Paper Conversion Chart

The table values are intended to guide you when speaking with our representatives. They’re not exact specifications, as there can be variances due to other paper qualities. Contact your Design Distributors representative today to ensure you’re choosing the correct paper for your project!