Paper weight calculator from GSM
Choose a paper size, enter the GSM and the number of sheets, and this paper weight calculator gives the weight of one sheet and of the whole stack.
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How to use the paper weight calculator
- Pick an A-series size, or choose Custom and type the width and height in millimetres.
- Enter the paper's GSM, which is printed on most paper packs.
- Enter the number of sheets.
- Press Calculate weight to see the weight of one sheet and the total in kilograms.
- Use the reference table under the results for quick A0 to A6 values.
How the paper weight calculator works
GSM stands for grams per square metre. It tells you how much one square metre of a paper weighs, so 80 GSM copy paper weighs 80 grams per square metre, and 300 GSM card weighs nearly four times as much for the same area.
To find the weight of a real sheet, the calculator works out the sheet's area in square metres from its width and height in millimetres, multiplies by the GSM, and then scales up to the number of sheets.
Formula
Sheet weight in grams = (width in mm × height in mm ÷ 1,000,000) × GSM. Dividing by 1,000,000 turns square millimetres into square metres.
Total weight in kg = sheet weight in grams × number of sheets ÷ 1,000.
Example
An A4 sheet is 210 by 297 mm, an area of 62,370 mm² or 0.06237 m². At 80 GSM it weighs 0.06237 × 80, about 4.99 g. A ream of 500 such sheets weighs 4.99 × 500 ÷ 1,000, about 2.495 kg before packaging.
An A0 sheet is very nearly one square metre, so at 80 GSM it weighs almost exactly 80 g. Each smaller A size is half the one before, so an A1 sheet weighs about 40 g.
Tips and common mistakes
Add the envelope for postage
Postal services price letters by weight bands. Add the envelope's weight to the paper weight before choosing a stamp.
Converting US paper weights
US papers often use a basis weight in pounds. 20 lb bond is about 75 GSM, so convert to GSM before using this calculator.
Entering US Letter size
For US Letter, enter 215.9 by 279.4 mm. For other sizes in inches, use the unit converter to get millimetres.
Count pages before a print run
Printing a long set of documents? Merge them into one PDF to see the total page count, then enter it as the number of sheets, or half of it for double-sided printing.
Check your printer's limit
Heavy card can jam home printers. Look up your printer's maximum GSM before buying thick paper.
Frequently asked questions
What does GSM mean?
Grams per square metre: the weight of one square metre of a paper. Higher GSM means heavier paper.
How much does an A4 sheet weigh?
About 4.99 g at 80 GSM, the most common office paper. At 100 GSM it is about 6.24 g.
Does higher GSM always mean thicker paper?
Usually, but not always. Thickness also depends on the paper's density and finish, so two papers of the same GSM can feel different.
Can I use a custom size?
Yes. Type any width and height in millimetres and the size switches to Custom automatically.