Why paper weight conversion is tricky
US paper weight (‘basis weight’) is measured in pounds per ream, but the ream size used for that measurement differs by paper grade — Bond paper uses a 17×22 inch sheet, Cover uses 20×26, and so on. This is why a ’20 lb’ bond sheet and a ’20 lb’ cover sheet are very different thicknesses. GSM (grams per square meter) avoids this problem by measuring a fixed area, which is why it’s the international standard.
How this calculator works
Enter the basis weight in pounds and select the paper grade. The calculator multiplies by the standard published conversion factor for that grade to estimate the equivalent GSM.
These are the commonly published industry conversion factors used by printers and paper suppliers; always confirm exact specifications with your paper supplier for critical print jobs.