Paper Weight Chart: GSM vs Lb by Grade

Paper Weight Chart: GSM vs Lb for Bond, Text, Cover, Index

To turn a US pound weight into grams per square meter, multiply by the factor for its grade: bond × 3.760, text × 1.480, cover × 2.704, index × 1.808. So 20 lb bond is 75 gsm, 80 lb text is 118 gsm, 80 lb cover is 216 gsm and 110 lb index is 199 gsm. The factors differ because each grade is weighed on a different sheet size.

Those four multipliers are not rules of thumb copied from a supplier chart. Each one falls straight out of the sheet size the US government's paper standard assigns to that grade, plus the exact length of an inch and mass of a pound. Below, every factor is worked from those inputs, a script reproduced all the results, and the arithmetic is shown so you can redo any line with a phone calculator.

The four multipliers at a glance

Keep this table and you can convert any US paper weight you will meet on a quote, a ream wrapper or a print shop's website.

Two readings of this table save most of the confusion. First, a bigger multiplier means a smaller basic sheet: bond is weighed on the smallest sheet, so each "bond pound" represents the most paper per square meter. Second, you cannot compare pound figures across rows. A 28 lb bond and a 70 lb text are almost the same paper (105 gsm against 104 gsm), even though one number is two and a half times the other.

Why the same "80 lb" can mean two different papers

A US paper weight is a basis weight: the weight in pounds of 500 sheets (one ream) cut to that grade's basic size. The government's paper standard states it in exactly those words on each grade page that carries a basis weight. The JCP D10 writing paper page, for example, reads "Basis weight: 17 by 22 inches, 500 sheets (pounds)" above its list of 12, 16, 18 and 20 lb weights. The JCP L10 gloss-coated cover page reads "Basis weight: 20 by 26 inches, 500 sheets" above 65, 80 and 100 lb.

The source is the US Government Publishing Office's Government Paper Specification Standards, No. 13 (September 2019), issued under the Joint Committee on Printing and listed as the current volume on GPO's vendor forms and standards page when we checked it on October 30, 2026. Part 5 of the document carries a box headed "Basic sizes for reams of 500 sheets":

So "80 lb text" means a ream of 25 × 38 inch sheets weighs 80 pounds, while "80 lb cover" means a ream of 20 × 26 inch sheets weighs 80 pounds. The cover sheet has 520 square inches against the text sheet's 950, so the same 80 pounds is spread over a little more than half the area. Per square meter, the cover paper is heavier by a factor of 950 ÷ 520 = 1.827.

That is the whole mystery of US paper weights. The pound figure tells you how heavy a ream is, but each grade's ream is a different size, so the figure only means something next to the grade name. Grams per square meter (gsm, written g/m² in standards) skip the ream entirely and weigh one square meter of the sheet, which is why gsm works as one common unit across grades, sheet sizes and countries.

Working each factor out from the sheet size

Every factor follows from one formula:

gsm per lb = 453.5924 g ÷ (500 × sheet area in m²)

The two unit constants come from NIST Special Publication 811, Appendix B.8: one inch is exactly 2.54 × 10⁻² m, so a square inch is 0.00064516 m², and one avoirdupois pound is 0.4535924 kg (NIST's table rounds to seven figures; the extra digits beyond that change nothing at the precision paper is made to).

The bond factor, step by step

1. Sheet area: 17 × 22 = 374 square inches.
2. In square meters: 374 × 0.00064516 = 0.241290 m².
3. A ream is 500 sheets: 500 × 0.241290 = 120.645 m² of paper.
4. One pound spread over that area: 453.5924 g ÷ 120.645 m² = 3.7597 g/m².

So each pound of bond weight adds 3.76 gsm, and 20 lb bond is 20 × 3.7597 = 75.19 gsm, which rounds to 75 gsm.

The other three, in the same steps

The "lb per gsm" column is the reverse trip. A European quote for 250 gsm, read as US cover, is 250 × 0.3698 = 92.5 lb cover.

Moving between US grades without touching gsm

Because every factor shares the same 453.5924 and 500, converting from one US grade to another reduces to a ratio of sheet areas:

• 1 lb bond = 950 ÷ 374 = 2.540 lb text
• 1 lb cover = 950 ÷ 520 = 1.827 lb text
• 1 lb index = 950 ÷ 777.75 = 1.221 lb text
• 1 lb index = 520 ÷ 777.75 = 0.669 lb cover

That explains the familiar pairing of 20 lb bond with 50 lb text: 20 × 2.540 = 50.8, close enough to treat the two as near equivalents when you order. It also explains why "110 lb index" and "73 lb cover" describe roughly the same card: 110 × 0.669 = 73.5.

The Letter sheet that weighs exactly one hundredth of a pound

There is a tidy check hidden in the bond basic size. A US Letter sheet (8.5 × 11 in) is exactly one quarter of a 17 × 22 sheet. So 500 Letter sheets of 20 lb bond weigh a quarter of 20 pounds: 5 lb. One sheet weighs 5 ÷ 500 = 0.01 lb, or 4.536 grams.

Run it from the metric side and you land in the same place: 75.19 gsm × 0.060322 m² (the area of a Letter sheet) = 4.536 g. When a paper chart and a kitchen scale disagree, this is the sum to try first, because it uses nothing but the definition of basis weight.

Equivalence chart for the common US weights

Each row below is one real weight in its home grade, converted to gsm and then into what the same paper would be called in the other three US grades. The home grade value is in bold. Values come from the factors above and are rounded to one decimal; the GPO grade codes in the last column show where each weight appears in the government standard.

Three pairs in the chart trip up buyers who order by the number alone:

• 100 lb text and 100 lb cover are not neighbours. 100 lb text is 148 gsm; 100 lb cover is 270 gsm, nearly double. Ordering "100 lb" without the grade name is how a brochure job arrives as card stock, or a postcard job arrives as floppy text paper.
• 80 lb text is lighter than 50 lb cover. 118 gsm against 135 gsm. The larger number is the lighter sheet.
• 90 lb index sits between 60 and 65 lb cover. It converts to 60.2 lb cover, so a 65 lb cover is the slightly heavier of the two.

The grade codes are there as a reality check rather than a buying guide. They show that these weights are standard enough for the US government to write a specification around them, which is a fair sign that a commercial printer will also carry something close.

Starting from gsm: what to ask for in pounds

Online printers, European paper merchants and most design software quote gsm first. This table runs the other way: pick the gsm on the quote, read across to the pound weight in each US grade. Values are the exact conversions; a merchant will round to the nearest weight it actually stocks.

Not every cell is a paper anyone sells. Nobody stocks a 270 lb text, and 21 lb cover would be too thin to behave like cover. The useful cells are the ones near the grade's normal range: up to about 150 gsm, read the bond and text columns; above about 175 gsm, read the cover and index columns. That boundary is not an official cutoff, it is simply where the GPO weight ranges change over: the heaviest text grade in the standard is 100 lb (148 gsm) and the lightest cover grade is 50 lb (135 gsm).

Two quotes, converted

A 350 gsm card from an online printer. You want to match it with a US merchant. 350 × 0.3698 = 129.4 lb cover, so the nearest US match is a 130 lb cover (351.5 gsm). As index it would be 350 × 0.5531 = 193.6 lb, heavier than the 170 lb top of the GPO index range, which tells you this is a cover-grade card, not an index card.

A 120 gsm letterhead. 120 × 0.2660 = 31.9 lb bond, so ask for 32 lb bond (120.3 gsm). If the merchant only lists text weights, 120 × 0.6756 = 81.1 lb text, and an 80 lb text (118.4 gsm) is within about 1.5 percent.

Which gsm for which print job

Paper choice is partly taste, so this table does not pretend to give one right weight per job. Instead it shows which grade the government standard assigns to each kind of work, using the "use information" paragraph printed on each grade page, and converts that grade's weight range to gsm. GPO notes that each use paragraph "is informational only and is not exclusively definitive of the end use", so treat the ranges as a well-documented starting point, then ask your printer what they run.

Business cards have no grade in the GPO book, and we found no standard that sets a weight for them, so the table does not invent one. What the book does tell you is the top of each card range: 170 lb index (307 gsm) and 130 lb smooth cover (352 gsm) are the heaviest weights it specifies. If a printer offers a card heavier than that, it is outside the government's grade list, which is fine, but it means the comparison has to happen in gsm or in caliper.

Postcards get their own section, because the rule that decides them is in the postal regulations, and it is written in thousandths of an inch.

The light end: when 40 lb text shows through

GPO's own warning on the A60 grade, that 40 lb uncoated text may not handle solid reverses or heavy halftones, is a weight problem and an opacity problem at once. Thin paper lets ink on the back show through. The standard sets a minimum opacity for most grades for exactly this reason; for D10 writing paper, for example, the minimum average climbs from 83 percent at 16 lb to 85 percent at 20 lb. If your piece has dark full-page images on both sides, moving up a weight is the cheap fix, and gsm is the number to move.

Postcards: the post office measures thickness, not weight

For anything you mail, the deciding number is not gsm or pounds. USPS Domestic Mail Manual section 201.1.2.1, read on October 30, 2026, says a card claimed at a card price must be:

• not less than 3.5 inches high, 5 inches long and 0.007 inch thick;
• at least 0.009 inch thick if it is more than 4.25 inches high or 6 inches long, or both; cards under that thickness become nonmachinable letters;
• not more than 0.016 inch thick.

A thousandth of an inch is a "mil" (and, in paper sales, usually a "point"). So the rule reads: 7 mils minimum for a standard postcard, 9 mils for an oversized one, 16 mils maximum.

Paper weight does not translate into thickness by any fixed formula, because coating, finish and fiber all change how much a given weight bulks up. But the GPO standard publishes an average thickness for every grade weight, with "a tolerance of ±0.0005 inch" (half a mil). That lets us test the common cover and index weights against the mail rules, using the government's own calipers:

The table makes three points that a weight chart alone cannot:

1. 65 lb gloss cover is under the postcard minimum on average. At 6.8 mils it is thinner than the 7-mil floor, while 65 lb uncoated cover at the same weight is 7.5 mils. The coating packs the same fiber into less thickness.
2. 80 lb cover is not enough for a 5 × 7 or 6 × 9 card, and even 100 lb can miss. The uncoated (8.2) and gloss (8.1) 80 lb averages are under 9 mils, and so is GPO's 100 lb matte-coated cover at 8.8.
3. "At the limit" rows are a coin toss. With a half-mil tolerance, an average of exactly 7.0 or 9.0 mils means some sheets in spec will be under the line.

These are GPO grade averages, not the paper your printer will use. A commercial stock with the same weight can measure differently. So for mail pieces, ask the printer for the caliper of the stock in mils or points, and compare it with 7, 9 and 16. If they quote only gsm or pounds, the table above shows why that is not enough.

Points, mils and calipers: the third number on a quote

Many US print shops sell card by "pt": 14 pt, 16 pt, 18 pt. That is a thickness, not a weight. In the paper trade a point is one thousandth of an inch, the same as a mil, which is how the GPO standard writes it ("thickness in mils"). The government book even lists some grades with no basis weight at all. Its JCP L70 coated one-side cover and L72 coated two-sides cover entries say "sold by thickness" and list calipers from 8 to 24 mils.

The practical consequence: you cannot convert pt to gsm with a multiplier. Two 16 pt cards can differ in weight because one is denser. Treat pt as an answer to "will this pass the postal rule and feel stiff?" and gsm as the answer to "how much paper am I buying, and what will it weigh in the mail?". When a quote gives only one of them, ask for the other.

Same weight, different feel: coating and thickness

The GPO thickness data also show why designers who buy by weight are sometimes surprised by the sheet that arrives. Compare grades at the same 80 lb text weight (118.4 gsm):

The uncoated sheet is 1.75 times as thick as the gloss sheet, with identical weight per square meter. That has real effects:

• Page count and spine width. Take a made-up 200-page book, which is 100 leaves. On the uncoated stock the paper stack is about 100 × 6.3 = 630 mils, or 0.63 inch; on the gloss stock it is 100 × 3.6 = 360 mils, about 0.36 inch. That gap is why a printer asks for the exact stock before giving you a spine width for the cover.
• Stiffness in the hand. Thicker sheets feel heavier, which is why an uncoated 80 lb text can feel more substantial than a gloss sheet of the same weight.
• Image sharpness. Coated grades carry finer screens: GPO lists halftones up to 175-line screen for gloss text against 150-line for uncoated text. The paper choice and the image resolution a print size needs work together.

Coating also changes colour. A coated and an uncoated stock behave differently on press, which is why printers ask for different colour profiles for each; the CMYK conversion guide covers which profile goes with which paper.

Where the official numbers disagree, and how much slack they allow

A source this precise still has rough edges, and they matter if you are using it to settle an argument with a supplier.

The bristol size appears twice, differently. The Part 5 summary box lists bristol at 25.5 × 28.5 inches. But the JCP L24 Vellum Bristol Cover grade page states its basis weight on 22.5 × 28.5 inch sheets. The two sizes give different factors: 1.935 gsm per lb on the larger sheet, 2.193 on the smaller. On the grade page's own size, its 57, 67 and 80 lb weights work out to 125, 147 and 175 gsm. Because of this conflict we left bristol out of the main charts. If a quote is in bristol pounds, ask the merchant which basic size they use.

Ledger also has two sizes. The summary box puts ledger at 24 × 36 inches, the same as newsprint, while the JCP J10 ledger grade page states its weights on 17 × 22 inch sheets, like bond. This is one more case where the grade name alone does not settle the sheet size, so ask.

Every weight carries ±5 percent. Each GPO grade page says "A tolerance of ±5% shall be allowed" on basis weight. So a perfectly acceptable 80 lb text can weigh anywhere from 112.5 to 124.3 gsm. Two papers sold as 80 lb text (118 gsm) and 120 gsm may not be different at all once the tolerance is counted, and a difference of a few gsm on a quote is noise, not a downgrade.

Rounded conversions drift. A chart that rounds 80 lb text to 120 gsm, or 100 lb cover to 270 gsm, is fine for ordering. The drift only bites when someone chains conversions (text to gsm to cover) using rounded steps. Use the area ratios in the earlier section for grade-to-grade moves and the error disappears.

The book is from 2019. Volume 13 is the newest edition GPO lists, with a list of changes dated February 2020. A future volume could revise grade weights or thicknesses, so check the date on the PDF if you are reading this guide much later.

Putting a weight on the order form

Here is a short routine that covers almost every paper conversation with a printer:

1. Name the grade every time you name a pound weight. "80 lb cover", never "80 lb".
2. Translate to gsm with the factor table, and write both on the brief: "80 lb cover (216 gsm)". It removes any doubt for an overseas or online printer.
3. For anything mailed, ask for caliper and check it against 7, 9 and 16 mils.
4. For anything bound, ask for caliper too, so the spine width is calculated from the real stock.
5. Allow 5 percent either way before calling two quoted weights different papers.
6. Ask for a paper sample or swatch book when feel matters. Weight, thickness and finish together decide how a piece feels, and no table replaces holding the sheet.

Paper is one of several things a print job can get wrong independently, alongside colour, resolution and trim, and two ink decisions sit on top of the paper choice. Uncoated press conditions can carry a lower total ink limit than coated ones (the profile table in our rich black guide lists 260 percent for Adobe's U.S. Web Uncoated v2 against 300 for U.S. Web Coated v2), which changes your rich black and total ink budget. A spot colour also looks different on coated and uncoated sheets, as the Pantone versus CMYK guide shows.

Once the stock is chosen, the file export is the last step that can undo it. Our PDF/X-1a versus PDF/X-4 export guide shows how to hand the printer a file that keeps your decisions intact.

For a heavy stock in particular, open the bleed, trim and safe area guide next. It works out document sizes with bleed for postcards, business cards and posters, which is the step where the card you just chose meets the cutting blade.

Paper weight questions printers get asked

How do I convert lb to gsm?

Multiply by the factor for the grade: bond 3.760, text 1.480, cover 2.704, index 1.808. The grade matters because each one is weighed as 500 sheets of a different size. 70 lb text × 1.480 = 103.6 gsm.

Is 80 lb text the same as 80 lb cover?

No. 80 lb text is 118 gsm and 80 lb cover is 216 gsm. Cover is weighed on a 20 × 26 inch sheet and text on a 25 × 38 inch sheet, so the same pound figure means almost twice the paper per square meter for cover.

What gsm is 20 lb bond copy paper?

75.2 gsm, from 20 × 3.7597. A single US Letter sheet of it weighs 4.536 grams, exactly one hundredth of a pound, because Letter is one quarter of the 17 × 22 inch bond sheet.

What is 100 lb cover in gsm?

270.4 gsm (100 × 2.7041). It is roughly equivalent to 150 lb index or 183 lb text. Across GPO's cover grades, the average thickness for 100 lb runs from 8.8 mils (matte coated) to 11.6 mils (uncoated laid finish), so not every 100 lb cover clears the 9-mil floor for an oversize postcard.

What gsm is a postcard?

There is no gsm rule. USPS sets thickness: at least 0.007 inch for a card up to 4.25 × 6 inches, at least 0.009 inch for a larger card, and no more than 0.016 inch. Ask the printer for the stock's caliper. On GPO's averages, 100 lb gloss and uncoated cover clear every size, 100 lb matte cover misses the oversize floor, and 65 lb gloss cover misses even the standard one.

Is pt the same as lb or gsm?

No. Points measure thickness (one point is a thousandth of an inch), not weight, so no fixed factor converts them. Two cards of the same point thickness can differ in gsm because of density and coating.

Why do online printers use gsm?

Grams per square meter weigh a fixed area, so the number means the same thing for every grade and sheet size. It is the easier unit for comparing quotes across grades and countries.

Is heavier paper always thicker?

Usually within one grade, but not across finishes. GPO's 80 lb text grades range from 3.6 mils (gloss coated) to 6.3 mils (uncoated) at exactly the same weight.

Standards and documents behind the numbers

• U.S. Government Publishing Office, Government Paper Specification Standards, No. 13 (September 2019), PDF retrieved October 30, 2026. Used for: the basic sizes box in Part 5 (page 128); basis weights, the ±5 percent tolerance and use information on the grade pages for JCP A60, A180, A240, A260, D10, G10, K10, L10, L23, L24 and J10; average thickness in mils from Part 5.
• U.S. Government Publishing Office, Forms and standards for vendors, checked October 30, 2026, listing Volume 13 (September 2019) as the newest edition, with Volume 12 (March 2011) and a Volume 13 list of changes dated February 2020.
• National Institute of Standards and Technology, NIST Guide to the SI, Appendix B.8: factors for units listed alphabetically, page updated August 18, 2025, read October 30, 2026. Used for: inch = 2.54 × 10⁻² m (exact) and avoirdupois pound = 4.535924 × 10⁻¹ kg.
• United States Postal Service, Domestic Mail Manual 201, Physical Standards, section 1.2.1, read October 30, 2026. Used for: card-price minimum and maximum thickness and dimensions.
• All gsm factors, conversions, equivalence rows, sheet weights and spine examples are our own arithmetic from those inputs, computed with a short script on October 30, 2026 and rounded for display. The job table converts GPO's grade weight ranges; it is not a recommendation from GPO or any printer.
• No primary source gave us a standard business card weight, commercial stock calipers, or bristol and ledger basic sizes beyond the two conflicting GPO listings, so the chart leaves them out.