Calculate paper thickness from weight and type. Convert GSM to mils, caliper, points, and compare paper stocks for printing and packaging projects.
The Paper Thickness Calculator converts between paper weight measurements (GSM, bond weight, cover weight) and physical thickness (mils, points, caliper). Understanding paper thickness is essential for designers, printers, and packaging professionals who need to select the right stock for business cards, brochures, book covers, and packaging.
Paper weight and thickness are related but not identical — a dense coated paper may be thinner than a lighter uncoated paper of the same weight. This calculator accounts for paper type (bond, offset, coated, uncoated, cardstock) to provide accurate thickness estimates based on bulk factor data from paper manufacturers.
Whether you're designing a multi-page booklet and need to calculate spine width, choosing cardstock for business cards, specifying packaging materials, or comparing paper samples from different suppliers, this tool gives you precise measurements in every standard unit used in the printing industry. It is especially useful when print specs, packaging tolerances, and finishing limits all depend on caliper instead of label weight alone.
Accurate paper thickness data prevents printing and binding mistakes, especially when the same weight can behave differently across coated and uncoated stocks.
It is useful because thickness, not just GSM, determines how a stack feels, how a spine measures, and whether a packaging or print spec will physically fit the final job.
Thickness (mils) = GSM × Bulk Factor / 25.4; 1 point = 1 mil = 0.001 inch = 0.0254 mm; Spine Width = Pages / 2 × Sheet Thickness; Stack Height = Sheets × Thickness
Result: 12.0 pt (0.012") / 0.305 mm thickness
300 GSM coated cover stock is approximately 12 points (0.012 inches) thick, suitable for premium business cards and book covers.
The paper industry uses multiple weight systems that can be confusing. In the US, paper is traditionally measured in pounds based on the weight of 500 sheets at the paper's "basis size," which varies by category. Bond paper uses 17×22" as basis, text/offset uses 25×38", and cover uses 20×26". This is why 80 lb text and 80 lb cover are very different thicknesses. The metric GSM system eliminates this confusion by measuring grams per square meter regardless of paper type.
For everyday printing, 80-100 GSM uncoated paper works well. Brochures and catalogs typically use 130-170 GSM coated stock. Business cards need 300-400 GSM or equivalent cover weight. Book pages range from 80-120 GSM depending on the desired feel — novel pages are usually thinner (80-90 GSM) while art books use heavier stocks (130-170 GSM).
Digital presses have specific paper requirements. Laser toner adheres differently to coated vs. uncoated stocks, and inkjet prints require paper with proper absorption properties. When specifying paper for digital printing, ensure the stock is rated for your printing method, as the wrong paper can cause jams, poor print quality, or adhesion problems.
GSM (grams per square meter) is a universal measurement. Pound weight varies by paper category: 20 lb bond = 75 GSM, while 80 lb cover = 216 GSM. GSM is more consistent for comparison.
Standard business cards are 14-16 pt (0.014-0.016"). Premium cards range from 16-32 pt. Ultra-thick cards can be 40+ pt with a duplexed or triplexed construction.
Caliper is the measured thickness of a single sheet, typically expressed in mils (thousandths of an inch) or points. One point equals one mil.
Coating fills in the paper fibers and compresses the sheet, making it denser and thinner for the same weight. A 100 GSM coated sheet is noticeably thinner than 100 GSM uncoated.
Divide total pages by 2 (for front and back of each sheet), multiply by the paper thickness, then add cover board thickness. This calculator does this automatically.
Standard copy/printer paper is 20 lb bond or 75-80 GSM, approximately 4 mils (0.004") thick.