Paper GSM to Thickness Converter
Convert paper grammage to caliper in microns, mils and millimetres, for the stock you are using.
What is GSM ↔ Thickness?
Grammage and caliper are not two names for the same quantity. GSM is mass per square metre and caliper is measured thickness; they are related by the stock's density, and the density is what makes the conversion interesting. 100 gsm of newsprint is about 143 µm thick while 100 gsm of coated gloss is about 100 µm, because the coating packs far more mass into the same volume. Paper merchants quote bulk — the inverse of density, in cm³ per gram — for exactly this reason, and a cover stock printing “300 gsm” can be a very different thickness from one that prints the same number.
How it works
A square metre of gsm grams of paper at density ρ occupies gsm/ρ cubic centimetres spread over 10,000 square centimetres, so the thickness is gsm/ρ microns — an identity that is exact for the assumed density and therefore has no error beyond the density assumption itself. Bulk is reported alongside the answer, and because a published caliper is a range rather than a constant, the output is labelled an estimate and the table of stocks shows how far the same grammage can diverge. Caliper can be entered in microns or mils, and the reverse conversion inverts the same identity.
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Examples
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