Why does the same GSM give different pound values?

US pound weights are defined by the weight of 500 sheets of a grade's basic size — and that basic size is different for Bond, Text, Cover, Index, etc. So 270 gsm is roughly 100 lb Cover but only 50 lb Bond.

Grams per square metre — the weight of a single square metre of the paper. It is grade-independent, which is why most of the world uses it.

Which is heavier, 80 lb Text or 80 lb Cover?

80 lb Cover. Cover stock uses a larger basic sheet, so an 80 lb Cover sheet is much thicker and heavier per square area than 80 lb Text.

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Paper Weight

Convert GSM to pounds — for the right paper grade.

US paper weights depend on the grade, because each one is measured on a different basic sheet size. Enter a weight and this converter gives the equivalent across Bond, Text, Cover, Index, Tag and Bristol.

Equivalent weight

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Equivalent weights, all grades

Grade	US weight	GSM

Equivalent weight means the same physical paper (same GSM) expressed in each grade's pound system. Two papers can read "80 lb" yet be very different — 80 lb Text is light, 80 lb Cover is card.

GSM is straightforward — grams per square metre, the same for every paper. US pounds are not: the number is the weight of a 500-sheet ream cut to that grade's "basic size", and each grade uses a different basic size.

Why 80 lb means two different things

80 lb Text is a fairly light book paper around 118 GSM. 80 lb Cover is a thick card around 216 GSM. They share a number only because Text is weighed at 25 × 38 inches and Cover at 20 × 26. GSM removes the confusion by measuring everything the same way.

The formulaGSM = lb × 1406.14 ÷ (basic width × basic height in inches). To go the other way, divide.

Basic sizes by grade

Grade	Basic size	Used for
Bond / Writing	17 × 22 in	Letterhead, copy
Text / Book	25 × 38 in	Book interiors, flyers
Cover	20 × 26 in	Covers, cards
Index	25.5 × 30.5 in	Dividers, tabs
Tag	24 × 36 in	Tags, tickets
Bristol	22.5 × 28.5 in	Postcards, board

Which should I quote?

If you work in metric or sell to overseas printers, quote GSM — it travels. If you buy from US mills, you'll see pounds plus the grade. Always pair a US pound figure with its grade, or it's ambiguous.

Frequently asked questions

Is GSM the same as thickness?

No. GSM is weight per area; thickness (caliper) also depends on how bulky the paper is. Two sheets at the same GSM can have different thickness, so for spine or stack height you need caliper, not weight.

What grade is "card stock"?

Usually Cover (measured at 20 × 26 in). Common card weights are 80 lb Cover (≈216 GSM) and 100 lb Cover (≈270 GSM).

How do I convert points (pt) or mils?

Those are thickness, not weight, so they don't convert directly from GSM. Ask your supplier for the caliper of the specific stock.

Are the numbers exact?

The conversion is exact for the basic-size definition; mills round to standard named weights, so the equivalents shown are the true value before rounding.