Caliper
The actual thickness of one sheet, not its weight. It decides how a card feels, how a fold behaves, and how wide a book spine becomes.
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What it is
Caliper is the physical thickness of one sheet, usually stated in microns, millimeters, mils, or paper points. In the paper trade, 10pt stock is about 0.010in thick. That point is one thousandth of an inch, not the 1/72in typographic point used for type size.
Reach for caliper when the thing has to occupy space: a business card needs a particular feel, a folded piece must fit a machine, or a perfect-bound book needs a spine width. Grammage tells you mass per area; caliper tells you thickness. A bulky uncoated sheet can be thicker than a dense coated sheet at the same gsm.
Gotcha: a catalog value is nominal, not a promise about every sheet. Humidity, compression, coating, and manufacturing tolerance move the measurement, and a bound stack does not always equal one-sheet caliper times page count. Get the printer's measured stock caliper before drawing a tight spine or package.
Ask AI for it
Write a production stock spec using ISO 534 thickness measurement. State the sheet caliper in microns and paper points, with 1 paper point = 0.001in, alongside the grammage in gsm. Calculate the estimated finished thickness for the assembled piece, identify every fold or binding operation affected by that bulk, and flag the estimate for a physical dummy check before the spine or package dieline is approved.