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Paper Weight Calculator
Use this free paper weight calculator to convert paper weight between gsm and pounds for bond, text, and cover paper, and to work out how much a sheet and a full ream weigh. Enter the gsm and paper type, or a sheet size and gsm, and get the weight in grams, kilograms, and pounds.
| Amount | Value |
|---|---|
| GSM | 75 gsm |
| Bond weight (17 × 22 in basis) | 20 lb |
| Text weight (25 × 38 in basis) | 51 lb |
| Cover weight (20 × 26 in basis) | 28 lb |
| One sheet | 4.52 g |
| Ream weight | 4.99 lb · 2.26 kg |
How it works
Paper weight is confusing because it is measured two different ways. GSM, grams per square meter, is the weight of one square meter of the paper, and it is the same everywhere in the world. Pounds, the number printed on a ream in North America, is the weight of 500 sheets at a basis size — and the basis size changes with the paper type. That is why the same paper can be 20 lb bond, 50 lb text, and 65 lb cover all at once.
To convert gsm to pounds, the calculator weighs a ream at the basis size. It takes the basis sheet area in square meters, multiplies by the gsm to get the weight of one basis sheet in grams, multiplies by 500 sheets, and divides by 453.592 to get pounds. The basis sizes are 17 by 22 inches for bond, 25 by 38 inches for text, and 20 by 26 inches for cover. Because the text basis sheet is much bigger than the bond basis sheet, the same gsm gives a bigger pound number in text than in bond.
Bond factor: lb = gsm × 0.266 · Text factor: lb = gsm × 0.676 · Cover factor: lb = gsm × 0.370
Sheet weight (g) = gsm × sheet width (m) × sheet height (m)
Ream weight = sheet weight × sheets per ream
The conversion factors fall out of the basis sizes. A bond basis sheet is 17 by 22 inches, or 0.2413 square meters, so one gsm is worth 0.266 lb in bond. A text basis sheet is 25 by 38 inches, or 0.6129 square meters, so one gsm is worth 0.676 lb in text. A cover basis sheet is 20 by 26 inches, or 0.3355 square meters, so one gsm is worth 0.370 lb in cover. Check it against a familiar number: 75 gsm bond is 75 × 0.266 = 20 lb, which is the standard 20 lb copy paper sold everywhere.
For ream weight, the calculator uses your actual sheet size instead of the basis size. An 8.5 by 11 inch sheet is 93.5 square inches, or 0.0603 square meters. At 75 gsm, one sheet weighs 75 × 0.0603 = 4.52 grams, and a ream of 500 weighs 4.52 × 500 = 2,262 grams, or 2.26 kilograms, which is 4.99 pounds. Change the sheet size, the gsm, or the sheets per ream and the weight scales in direct proportion: double the gsm and the ream weighs twice as much.
Two practical notes. First, always compare papers in the same unit: compare gsm with gsm, or bond with bond. Comparing 20 lb bond with 20 lb cover is meaningless, because the two use different basis sizes. Second, gsm measures weight, not thickness. Two papers at the same gsm can feel different if one is coated and the other is not, but as a rough guide, 80 gsm is about 0.1 millimeters thick, 200 gsm is about 0.2 millimeters, and 300 gsm is about 0.3 millimeters.
Worked example
You buy a ream of standard copy paper: 8.5 by 11 inches, 75 gsm, 500 sheets.
Step 1: Sheet area — 8.5 × 11 = 93.5 square inches, which is 0.0603 square meters.
Step 2: One sheet — 75 × 0.0603 = 4.52 grams.
Step 3: Ream weight — 4.52 × 500 = 2,262 grams, or 2.26 kg, which is 4.99 lb.
Step 4: Bond weight — 75 × 0.266 = 19.95, or 20 lb bond.
The result is 20 lb bond, 4.52 g per sheet, and a 4.99 lb ream (2.26 kg) — exactly what the calculator shows for those inputs.
FAQ
What does gsm mean for paper?
GSM means grams per square meter, the weight of one square meter of the paper. A higher gsm means thicker, heavier paper: copy paper is usually 75 to 80 gsm, a magazine page is about 100 to 130 gsm, a postcard is about 250 to 300 gsm, and a business card is about 300 to 350 gsm. GSM is the same everywhere, which is why it is the easiest way to compare papers from different makers.
How many pounds is 80 gsm paper?
It depends on the paper type, because pounds are measured against a basis size that changes by type. 80 gsm bond paper is about 21 lb bond, 80 gsm text paper is about 54 lb text, and 80 gsm cover paper is about 30 lb cover. Use the paper type dropdown in the calculator above: the same gsm gives a different pound weight for bond, text, and cover, and comparing numbers across types without converting is a common mistake.
How much does a ream of copy paper weigh?
A ream of 500 sheets of 8.5 by 11 inch, 75 gsm copy paper weighs about 5 pounds, or 2.26 kilograms. Each sheet weighs about 4.5 grams. Heavier paper weighs more in the same proportion: a ream of 100 gsm paper the same size weighs about 6.6 pounds. Enter your sheet size, gsm, and sheets per ream in the calculator above for the exact weight of your paper.
What is the difference between bond, text, and cover paper?
Bond, text, and cover are three families of paper, and each has its own basis size for measuring pound weight: bond uses 17 by 22 inch sheets, text uses 25 by 38 inch sheets, and cover uses 20 by 26 inch sheets. Bond is everyday office paper, text is the lighter paper used for books, brochures, and magazines, and cover is the stiff paper used for covers, postcards, and business cards. Because the basis sizes differ, 20 lb bond, 50 lb text, and 65 lb cover are all roughly the same thickness.
How thick is paper in gsm?
GSM measures weight, not thickness, but the two track closely for the same kind of paper. As a rough guide, 80 gsm copy paper is about 0.1 millimeters thick, 200 gsm card is about 0.2 millimeters, and 300 gsm card is about 0.3 millimeters. Coated paper is a little thinner than uncoated paper at the same gsm, because the coating adds weight without much thickness. For an exact thickness, ask the paper maker for the caliper, which is the thickness in thousandths of an inch or in microns.