Paper weight explained: text, cover & gsm

What a paper's “weight” actually measures

A paper's pound rating does not describe the sheet in your hand. It describes 500 sheets — one ream — of that paper at its basis size, the large uncut parent sheet the mill works in. Weigh that ream, and whatever it reads in pounds becomes the paper's name. Eighty pounds on the scale, and the paper is “80 lb” forever after.

That would be a perfectly reasonable system if every paper used the same basis size. None of them do. Each family — text, cover, bond, index, tag — grew up in a different corner of the industry with a different parent sheet, and each one kept its own. The pound number is relative to a basis size you cannot see and were never told.

So “80 lb” is not a measurement. It is a label that means something only once you know which family it belongs to. Drop the family name and the number is close to useless — which is exactly how most paper conversations go wrong. If a term here is new, our print glossary keeps the definitions short.

Why 80 lb text and 80 lb cover are different papers

Text paper's basis size is 25 × 38 inches — 950 square inches per sheet. Cover paper's basis size is 20 × 26 inches — 520 square inches. A ream of text stock has nearly twice the surface area of a ream of cover stock.

Now put both reams on the scale and make each read 80 pounds. The text ream spreads those 80 pounds across almost double the area, so every sheet has to be much thinner. The cover ream concentrates the same 80 pounds into far less area, so every sheet is much thicker. Same number, same scale reading, two completely different papers.

In metric the gap is stark. 80 lb text lands around 118 gsm — a little heftier than office copy paper, the classic flyer weight. 80 lb cover lands around 216 gsm — stiff, postcard territory, roughly the paper of a nice greeting card. Nearly twice the sheet, hiding behind an identical label.

This is the single most common source of print confusion, and it is why every real spec names the family: not “80 lb,” but “80 lb text” or “80 lb cover.” When someone quotes you a bare number, ask which family. It is not a nitpick — it is the difference between a flyer and a postcard.

The five paper families and what each is for

Five families cover essentially everything in commercial print. Each has its own basis size, its own typical range, and its own jobs.

• Text / Book — basis 25 × 38 in.

  The everyday printing paper, typically 60 to 100 lb (roughly 89 to 148 gsm). Flyers, brochures, booklet interiors, sell sheets, posters. Folds cleanly and covers most of what a business prints.

• Cover / Card — basis 20 × 26 in.

  Stiff stock, typically 65 to 130 lb (roughly 176 to 351 gsm). Postcards, business cards, booklet covers, menus, folders — anything that has to stand on its own or survive a mailbox. Card thickness is usually quoted in points instead, which our business card stocks guide covers in depth.

• Bond / Writing — basis 17 × 22 in.

  Thin, uncoated, built for writing and office equipment. Typically 20 to 32 lb (roughly 75 to 120 gsm). Letterhead, copy paper, carbonless forms, envelopes. It has the smallest basis size of the group, which is why bond numbers look so low next to everything else.

• Index — basis 25.5 × 30.5 in.

  Stiff, uncoated, slightly toothy. Typically 90 to 140 lb (roughly 163 to 253 gsm). Tab dividers, record cards, file inserts — jobs needing rigidity and a writable surface.

• Tag — basis 24 × 36 in.

  Tough and tear-resistant, built to hang and take abuse. Hang tags and shipping tags. Less common on a typical business job, but the right answer when a piece has to survive handling.

These ranges are typical, not absolute — mills stock weights above and below them, and any given press has its own limits on what it will run.

GSM: the escape hatch that actually works

Gsm — grams per square meter — is the fix. It ignores basis sizes entirely and asks one question: how much does a square meter of this paper weigh? Every paper gets measured against the identical square meter, so gsm numbers compare directly. Higher gsm always means more paper. No family to remember, no parent sheet to look up, no trap.

Converting is one multiplication. Multiply the pound number by the factor for its family: about 1.48 for text/book, 2.70 for cover/card, 3.76 for bond/writing, 1.81 for index, and 1.63 for tag. Divide by the same factor to go the other way. Our paper weight converter handles it for you, family and all.

Those factors also expose some useful equivalences. 20 lb bond is 20 × 3.76, about 75 gsm. 50 lb text is 50 × 1.48, about 74 gsm. Those are the same paper wearing two labels — standard copy paper, called one thing in the office supply aisle and another by a printer. 24 lb bond and 60 lb text are near-twins too, both around 90 gsm.

Treat converted numbers as round. Gsm derived from a pound rating is arithmetic, and real paper comes off the mill with a tolerance around it.

What weight for what piece

Rules of thumb, not rules. The right weight depends on how a piece is handled, mailed, and looked at.

• Flyers and sell sheets

  100 lb gloss text (about 148 gsm) is the workhorse — substantial in hand, little show-through with two-sided ink. Drop to 80 lb text for high-volume handouts where cost per piece matters more than feel. See flyers.

• Brochures

  80 to 100 lb text. Folding is the constraint: text stock folds cleanly, while heavy cover stock needs a score first or the fold will crack along the spine. More on brochures.

• Postcards

  Cover stock, and mailing decides it. A mailed card needs rigidity to survive automated equipment, and the USPS sets thickness standards that change from time to time — confirm the current requirement before you commit to a stock. See postcards.

• Menus

  Cover stock if the menu is reused, with a coating or lamination so it wipes down. Text stock if it is printed fresh daily or tucked into a takeout bag. See menus.

• Letterhead

  24 lb bond (about 90 gsm) is the classic. It also has to run through your own office printer without jamming, and that ceiling matters more than the look. See letterhead & envelopes.

• Booklet interior vs. cover

  Two specs in one piece. Interiors run text stock — heavier resists show-through but adds bulk and mailing weight. Covers run cover stock for stiffness. A self-cover booklet uses one text stock throughout: lighter and cheaper, but it reads less finished. See booklets & catalogs.

If you would rather answer a few questions than memorize a chart, our paper picker walks you to a stock based on what you are printing.

Caliper vs. weight: thickness is a different measurement

Weight and thickness are related, but they are not the same thing, and assuming they are will burn you. Caliper is the actual thickness of a sheet, measured with a micrometer and expressed in points or mils, where one point equals one thousandth of an inch. A 14pt card is 0.014 inches thick. That is a physical fact about the sheet, not a number derived from a ream on a scale.

Two papers can share a pound rating and a gsm and still measure differently. The reason is bulk — how much thickness a paper gets per unit of weight — and the biggest lever on it is coating. Coating is mineral, and mineral is heavy. A coated sheet spends part of its weight on a thin, dense surface layer, so a coated 100 lb cover generally measures thinner than an uncoated 100 lb cover. The uncoated sheet is bulkier: same weight, more thickness, more perceived heft.

This is exactly why cards get specified in points rather than pounds. When someone says “thick,” they mean caliper, so the industry quotes the thing they actually mean. Coating changes how ink sits on the sheet too — our print finishes guide covers that side. When thickness is critical, ask for the caliper spec or a physical sample. Mill to mill, the numbers move.

80 lb vs 100 lb: what the jump actually buys you

Compare within a family and the number finally behaves. 100 lb text is more paper than 80 lb text — about 148 gsm against 118, roughly 25 percent more sheet. The real question is what that 25 percent buys.

Mostly it buys opacity and hand. Opacity is show-through: how much of the ink on the back of a sheet you can see from the front. Print a dark, ink-heavy design on both sides of 80 lb text and the back ghosts through. The same design on 100 lb text mostly does not. Hand is the harder-to-name quality of a piece not flopping over when someone picks it up. A 100 lb text flyer holds itself. An 80 lb one bends.

Where 80 lb still wins: high-volume handouts, inserts, booklet interiors where bulk works against you, and anything mailed in quantity — because heavier paper is heavier in the literal, postage-paying sense. Weight is a cost you pay twice, once at the printer and once at the post office.

Same logic on the cover side. 100 lb cover (about 270 gsm) against 80 lb cover (about 216 gsm) is the difference between a card that stays flat through the mail and one that arrives with a bend. And there are diminishing returns — past a point, more paper stops reading as quality and starts reading as heavy.

How to spec paper so you get what you pictured

Three habits keep you out of trouble.

First, always say the family. “100 lb” is not a spec. “100 lb gloss text” is. Add the gsm for a second lock on it — a spec reading “100 lb gloss text (148 gsm)” cannot be misread by anyone. If a quote you are comparing lists a bare pound number, that quote is ambiguous, and two vendors may not be pricing the same paper at all.

Second, describe the job, not just the paper. “A two-sided leave-behind that lives in a folder for a month” tells a printer more than any weight you could name, because it implies opacity, hand, and finish all at once. The number should be the output of that conversation, not the input.

Third, handle it before you buy a thousand of it. Coating, brightness, and bulk can make two identical 148 gsm sheets feel like different papers. Ask for samples when you request a quote and put your top two side by side.

We design print & stationery in Buffalo, MN and produce it with trusted print partners, and we spec every job by family and gsm rather than a bare number — because that is the only version that survives a handoff. Tell us what the piece has to do and we will recommend the stock.

Frequently asked questions

• What is the difference between 80 lb and 100 lb paper?

  Within the same family, 100 lb is simply more paper — about 25 percent more than 80 lb. In text stock that is roughly 148 gsm against 118 gsm. The extra weight buys opacity, so two-sided ink shows through less, and hand, so the piece does not flop over. It also costs more to buy and more to mail. Across different families, the comparison is meaningless.

• Is 80 lb cover thicker than 80 lb text?

  Much thicker — roughly twice the paper. Text stock is rated on a 25 by 38 inch basis sheet and cover stock on a 20 by 26 inch sheet, so a ream of text spreads the same 80 pounds across nearly double the area. In metric terms, 80 lb text is about 118 gsm and 80 lb cover is about 216 gsm. Same label, different papers.

• What does gsm mean on paper?

  Gsm stands for grams per square meter: the weight of one square meter of that paper. Because every paper is measured against the identical square meter, gsm numbers compare directly, and higher always means more paper. That is what makes gsm the reliable escape hatch from the US pound system, where each stock family uses a different basis size.

• What is the difference between text stock and cover stock?

  Text stock is everyday printing paper — flyers, brochures, booklet interiors — typically 60 to 100 lb, and it folds cleanly. Cover stock is stiff card — postcards, business cards, booklet covers, menus — typically 65 to 130 lb, and it usually needs scoring before it will fold without cracking. They use different basis sizes, so their pound numbers are not comparable.

• How do I convert paper weight from lb to gsm?

  Multiply the pound number by the factor for its family: about 1.48 for text and book, 2.70 for cover and card, 3.76 for bond and writing, 1.81 for index, and 1.63 for tag. Divide by the same factor to go from gsm back to pounds. So 100 lb text is about 148 gsm, while 100 lb cover is about 270 gsm.