How to Use the Paper Weight Calculator
When preparing print jobs or bulk mailings, knowing the total weight of a paper stack in advance helps you estimate shipping costs and choose the right box or envelope. This calculator converts U.S. basis weight (lb) to metric gsm, then multiplies by sheet area and count to get the total weight.
Basis weight is the weight in pounds of 500 sheets at a paper category's standard ream size — 17×22 in for Bond, 25×38 in for Text/Book, and 20×26 in for Cover. Because the reference sheet size differs by category, the same lb number means a different actual thickness depending on the category, so this calculator applies a category-specific multiplier (Bond ×3.76, Text/Book ×1.48, Cover ×2.708) to estimate the equivalent gsm before calculating weight.
For example, standard 20 lb bond copy paper works out to about 75 gsm — a stack of 500 Letter-size sheets weighs roughly 5.2 lb. Heavier cover stock used for postcards or business cards, like 80 lb cover, converts to roughly 216 gsm and feels noticeably thicker and heavier for the same sheet count.
If you're mailing a bulk print job, checking the total stack weight against USPS postage weight tiers ahead of time can help you avoid unexpected postage charges — switching to a lighter basis weight or splitting the mailing into smaller batches can help keep you under a rate break.
Frequently Asked Questions
Basis weight is the U.S. weight (in lb) of 500 sheets at a paper category's standard ream size, and it converts to gsm differently for each category — for example, 20 lb bond is about 75 gsm.
Yes, add the weight of the envelope or box to the calculated paper stack weight to get a rough estimate of your total shipping weight for postage purposes.