GSM Grammage vs. Paper Caliper
Comparing 2 standards across 14 specifications. 14 key differences identified.
GSM (Grams per Square Meter / g/m², standardized under ISO 536) is the universal metric measure of paper areal density. Defining the exact physical weight in grams of a 1-square-meter (A0) sheet, it provides a linear, universal scale that eliminates the confusion of different paper grades and sheet sizes.
Paper Caliper (measured in Points / pt / mils / microns, standardized under TAPPI T 411 and ISO 534) is the direct measurement of paper thickness using a precision motorized micrometer under standardized mechanical pressure. In North American commercial packaging and business card production, 1 Point equals one-thousandth of an inch (0.001 in / 25.4 µm).
Specification Comparison Table
14 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standard Metric Unit
|
g/m² (Grams per Square Meter — GSM) | — |
|
Standard Copy Paper
|
80 gsm (Standard European/Asian office paper — ~20 lb to 22 lb US Bond) | — |
|
Premium Stationery / Letterhead
|
100 to 120 gsm (Smooth premium corporate letterhead / resume paper) | — |
|
Flyers & Magazine Pages
|
130 to 170 gsm (Semi-gloss / silk coated marketing flyers and magazine interiors) | — |
|
Greeting Cards & Booklet Covers
|
200 to 250 gsm (Medium cardstock / folder covers) | — |
|
Heavy Business Cards & Postcards
|
300 to 350 gsm (Heavy rigid cardstock / luxury business cards) | — |
|
Rigid Packaging Boxboard
|
400+ gsm (Folding cartons, cosmetic boxes, presentation covers) | — |
|
Standard Point Definition
|
— | 1 Point (pt) = 0.001 inch = 1 mil = 25.4 micrometers (µm) |
|
Standard 20 lb Copy Paper Caliper
|
— | Approx. 3.8 to 4.0 pt (0.004 in / ~100 µm) |
|
Standard Book Paper Caliper (50 lb Text)
|
— | Approx. 4.5 to 5.2 pt (High-bulk paper reaches 5.5+ pt) |
|
Paperback Book Cover (C1S)
|
— | 10 pt to 12 pt (0.010 to 0.012 in / 254 to 305 µm) |
|
Standard US Postal Postcard Minimum
|
— | 7.0 pt (0.007 in / 178 µm — USPS minimum thickness to machine-sort) |
|
Standard Commercial Business Card
|
— | 14 pt to 16 pt (0.014 to 0.016 in / 355 to 406 µm) |
|
Ultra-Luxury Edge-Painted Business Card
|
— | 32 pt to 36 pt (0.032 to 0.036 in / ~800 to 900 µm — double-thick duplexed stock) |