Paper Weight and Thickness: The Complete US Guide for Printing and Mailing

Pick up two pieces of paper both labeled "80 lb" and they feel completely different. One is thin and flexible, barely stiffer than copy paper. The other is thick and substantial, closer to a greeting card. They carry the same number but they are genuinely different materials measured on genuinely different scales. That confusion is built into the US paper weight system, and it causes real problems when businesses order stationery, letterhead, or envelopes without understanding it.

This guide explains paper weight in plain terms across all three measurement systems you will encounter (lb, GSM, and pt), covers every weight range and what each one is used for, connects paper weight to USPS mailing requirements, and explains how paper weight affects the envelope you need and the postage you pay.

What real customers say about Business Envelopes

The following reviews come directly from verified buyers on businessenvelopes.com.

★★★★★ Anonymous - Verified buyer, Double Window Check Envelopes
"The envelopes I ordered came in and they were absolutely perfect. Best ones I have ever ordered. The glue on the back actually seals the envelope and the overall quality of the paper feels much more substantial than envelopes I have ordered from sites like Office Depot. Definitely will be re-ordering."

★★★★★ Cindy - Steller Management, Verified buyer
"Amazing company! Excellent service and great products, especially the double window envelopes. Gives my checks the professional look. I highly recommend BusinessEnvelopes.com."

★★★★★ Cathy - Horizon Home Care Service, Verified buyer
"Amazing company! I was able to design my custom envelope and it was printed as expected. Thank you!"

★★★★★ Verified buyer -#10 Security Tinted Envelopes
"I have now ordered from businessenvelopes.com four times. Every time my order is perfect and it always looks exactly as ordered. Business Envelopes exceeds my expectations on shipping and the product is excellent. I will continue doing business with Business Envelopes."

★★★★★ Verified buyer -#10 Self Seal Tinted Envelopes
"I switched from another brand to these because they were half the cost. I did not sacrifice anything in quality. These are security-lined and the adhesive is as good, maybe better, than the more expensive brand."

Why the US paper weight system is confusing

The pound (lb) system measures the weight of 500 sheets of paper at the standard parent sheet size for that paper category. Different paper categories use different parent sheet sizes. That is the root of all the confusion.

Bond paper uses a parent sheet of 17 x 22 inches. Text paper uses 25 x 38 inches. Cover paper uses 20 x 26 inches. Because those parent sheets are different sizes, the same number of pounds produces different actual thickness and density depending on which category is being measured.

This is why an 80 lb text sheet and an 80 lb cover sheet feel completely different. Both are correctly labeled. Neither measurement is wrong. They are simply measured on different scales using different base sheet sizes, which makes comparing them by lb number alone meaningless.

The three paper measurement systems:

Pound weight (lb): Useful for comparing papers within the same category (80 lb cover vs 100 lb cover) but misleading across categories.

GSM (grams per square meter): The most reliable cross-category comparison tool. GSM measures actual paper density consistently across all paper types. A 216 gsm sheet is always 216 gsm regardless of whether it is labeled text, cover, or bond. Use GSM when comparing papers from different categories or international suppliers.

Points (pt): A measure of physical thickness, not weight. One point equals 0.001 inch. A 14 pt card is 0.014 inches thick. Points are used for cardstock and are the most useful measurement for understanding USPS direct mail compliance.

The practical rule: use lb within the same category. Use GSM across categories. Use pt when physical thickness determines mail classification.

Bond paper: the letterhead and office paper category

Bond paper has a parent sheet of 17 x 22 inches. This is the category for office paper, letterhead, and general correspondence.

20 lb bond (75 gsm): Standard copy paper. Fine for internal documents and drafts. Not appropriate for client-facing correspondence.

24 lb bond (90 gsm): The professional standard for business letterhead. Noticeably more substantial than 20 lb copy paper. Feeds reliably through standard office laser and inkjet printers. This is the weight that matches correctly with a standard #10 envelope. A single sheet of 24 lb bond plus a standard #10 envelope comes in just under one ounce.

28 lb bond (105 gsm): Premium business stationery. Perceptibly heavier than 24 lb. Used by law firms, financial advisors, and medical practices where the physical feel of the paper communicates something about the quality of the practice. Most standard office printers still feed this weight reliably from the manual tray.

32 lb bond (120 gsm): Heavyweight stationery. Some office printers require manual feed at this weight. Used for premium legal documents, formal proposals, and high-end correspondence. The combined weight of a multi-page letter on 32 lb bond can push past one ounce, so verify before assuming one stamp covers the full piece.

Text weight paper: brochures, flyers, and book pages

Text paper has a parent sheet of 25 x 38 inches. This is the category for commercial printing applications where a quality step up from copy paper is needed without the rigidity of cardstock.

60 to 70 lb text (90 to 105 gsm): Lightweight commercial printing. Newsletter pages, book interiors, and mass-distributed flyers where per-piece cost matters more than physical presence.

80 lb text (118 gsm): The most common commercial text weight. Brochure interiors, magazine pages, and promotional inserts. Better feel than copy paper but not rigid enough to hold its shape independently.

100 lb text (148 gsm): Premium text weight. High-quality brochure interiors, art book pages, and upscale informational pieces.

Text weight paper should not be used for any piece mailed without an envelope. USPS requires postcards to meet minimum thickness and basis weight standards that text weight paper generally does not meet.

Cover weight paper: cardstock for cards, postcards, and business cards

Cover paper has a parent sheet of 20 x 26 inches. This is the category for all cardstock applications: business cards, postcards, greeting cards, report covers, and anything that needs structural rigidity.

65 lb cover (176 gsm, approximately 7 to 9 pt)

The lightest cover weight in common use. Folds relatively easily without scoring. Used for folded greeting cards, lightweight menus, and casual note cards. Borderline for USPS postcard mailing: 80 lb cover or heavier is more reliable for automated postal processing.

80 lb cover (216 gsm, approximately 8 to 10 pt)

The industry standard for greeting cards, standard postcards, and general cardstock printing. A 4 x 6 inch postcard at 80 lb cover sits within the USPS postcard thickness window (0.007 to 0.016 inch) and processes cleanly through automated sorting. Most desktop printers handle this weight through the standard paper tray. This is the weight that matches the regular envelopes and colored envelopes most commonly used for card mailings.

100 lb cover (270 gsm, approximately 10 to 12 pt)

Premium cardstock. The step up from 80 lb is immediately perceptible. Used for formal invitations, premium report covers, and flat announcement cards where physical quality signals importance. Most desktop printers require manual feed at this weight.

110 lb cover (284 to 300 gsm, approximately 12 to 14 pt)

Heavyweight cover stock for premium business cards, specialty packaging, and certificates. Requires commercial printing equipment in most cases.

Points and caliper: the measurement that matters most for direct mail

USPS does not classify mail by lb or gsm. It classifies mail by physical dimensions including thickness measured in inches, which is what the point system describes.

14 pt (approximately 310 gsm, 0.014 inch)

The commercial standard for business cards and direct mail postcards. Resists bending in wallets, holds edges cleanly after trimming, and processes cleanly through postal sorting equipment.

16 pt (approximately 350 gsm, 0.016 inch)

Premium standard for business cards and quality postcards. At 16 pt a piece has a premium feel that signals quality before it is read.

18 pt and above (400 gsm and up)

Ultra-premium cardstock for luxury business cards and specialty packaging. Requires commercial production equipment.

The USPS thickness rules:

For a postcard to qualify for the First-Class postcard rate of 61 cents, thickness must be between 0.007 inch and 0.016 inch. Standard 14 pt cardstock at 0.014 inch fits cleanly. Standard 16 pt at 0.016 inch sits exactly at the maximum and remains compliant.

For postcards larger than 4.25 x 6 inches, USPS requires a minimum thickness of 0.009 inch. This rules out lighter stocks for oversized direct mail pieces and is why direct mail professionals specify 14 pt or heavier for any piece mailed without an envelope.

Complete paper weight reference table

US weight	GSM	Point equivalent	Best uses
20 lb bond	75 gsm	3 to 4 pt	Copy paper, internal documents
24 lb bond	90 gsm	4 to 5 pt	Professional letterhead, stationery
28 lb bond	105 gsm	5 to 6 pt	Premium letterhead, formal correspondence
80 lb text	118 gsm	6 pt	Brochure interiors, newsletters
100 lb text	148 gsm	7 pt	Premium brochure pages, art book interiors
65 lb cover	176 gsm	7 to 9 pt	Folded greeting cards, menus, light note cards
80 lb cover	216 gsm	8 to 10 pt	Greeting cards, standard postcards
100 lb cover	270 gsm	10 to 12 pt	Formal invitations, premium report covers
14 pt	310 gsm	14 pt	Business cards, direct mail postcards
16 pt	350 gsm	16 pt	Premium business cards, quality postcards
18 pt+	400+ gsm	18 pt+	Luxury cards, specialty applications

 

How to convert between paper weight systems

Text lb to GSM: Multiply lb by 1.48. (80 lb text × 1.48 = approximately 118 gsm)

Cover lb to GSM: Multiply lb by 2.71. (80 lb cover × 2.71 = approximately 216 gsm)

GSM to text lb: Divide GSM by 1.48.

GSM to cover lb: Divide GSM by 2.71.

Points to inches: Divide pt by 1000. (14 pt ÷ 1000 = 0.014 inch)

These are estimates. Actual thickness varies slightly by fiber composition, coating, and manufacturing process. Two sheets labeled "100 lb cover" from different mills can have slightly different caliper measurements. For USPS compliance, measure the actual finished piece rather than relying solely on specification conversions.

How paper weight affects your envelope and postage

Letterhead and the #10 envelope

A single sheet of 24 lb bond letterhead folded in thirds in a #10 envelope weighs just under one ounce. One First-Class Forever stamp (78 cents) covers it. Add a second page on 24 lb bond or switch to 28 lb bond and the combined weight approaches one ounce more quickly. Add a reply envelope inside and the piece almost certainly exceeds one ounce, requiring additional postage at 29 cents per extra ounce. For businesses using window envelopes for billing and invoicing, the same weight logic applies: weigh a fully assembled sealed sample before buying stamps for any large run.

Card weight and invitation envelopes

A single 5 x 7 inch card at 80 lb cover in a standard envelope typically weighs under one ounce. A full invitation suite with multiple cards at 100 lb cover, an RSVP card, and a pre-stamped return envelope can easily reach 1.5 to 2 ounces. The postage difference between one ounce (78 cents) and two ounces ($1.07) on a run of 150 invitations is $43.50 in unplanned cost. Always weigh the complete assembled sealed envelope before purchasing stamps for any invitation mailing. All invitation envelope sizes are available at all-sizes-envelopes.

Documents that cannot be folded

For any document that must arrive flat and unfolded, clasp envelopes in 6 x 9, 9 x 12, 10 x 13, and 9.5 x 12.5 inch sizes hold standard documents completely flat. The postage for this format starts at $1.63 as a USPS flat, which is higher than the letter rate. For premium 28 or 32 lb bond documents mailed regularly, this is the correct budgeted cost per piece.

Documents that cannot arrive damaged

For legal filings, signed contracts, medical records, and any document where arrival condition is non-negotiable, Tyvek envelopes are made from DuPont high-density polyethylene fiber. They resist tearing, puncture, and moisture from the material structure itself. Available in 6 x 9, 9 x 12, 10 x 13, and 10 x 15 sizes, all with peel-and-seal closure.

Financial documents

Any correspondence carrying checks, account numbers, or financial data belongs in a check envelope with security tinting. The interior pattern blocks document contents from being visible when the envelope is held to light. Available in double-window formats compatible with QuickBooks, Quicken, and Sage.

Self seal for volume mailing programs

For any organization mailing letterhead or invoices at volume, self seal envelopes remove the moisture activation step from the sealing process. Peel-and-press and flip-and-stick closures available in #6 3/4, #9, #10, 6 x 9, 9 x 12, 10 x 13, and 10 x 15 sizes.

Which paper weight to use for each print project

Business letters: 24 lb bond (90 gsm) in a #10 envelope. 28 lb bond for premium correspondence. Window envelopes eliminate the addressing step for recurring invoices and statements.

Invoices and billing: 20 to 24 lb bond feeds through laser printers and window envelopes reliably. The address on the printed document shows through the window without any additional addressing step.

Greeting cards: 80 lb cover (216 gsm) for standard folded cards. Match to the appropriate envelope size from the all sizes catalog.

Business cards: 14 pt commercial standard. 16 pt for premium. Requires commercial printing equipment, not desktop printers.

Direct mail postcards: 14 pt or 80 lb cover minimum for USPS machinable processing. Anything lighter risks non-machinable classification and the 49-cent surcharge per piece.

Contracts and unfolded documents: Clasp envelopes or Tyvek envelopes in 9 x 12, 10 x 13, or 10 x 15 sizes.

Branded outgoing correspondence: Custom printed envelopes with logo and return address on the stock. Available across #6 3/4, #9, #10, #11, 6 x 9, 9 x 12, and 10 x 13 sizes.

Direct mail campaigns: Colored envelopes in wove and starburst formats in #6 3/4, #9, #10, 6 x 9, and 9 x 12 sizes for visual impact in a mail pile.

What makes Business Envelopes different

Business Envelopes has served 53,526 customers across the US since 1997 as a family-owned business. Here is what matters for anyone selecting envelopes to match their paper and print choices.

Every commercial size in one catalog. #10 envelopes for letterhead and billing. Window envelopes for invoicing. Clasp envelopes for flat document mailing. Tyvek envelopes for documents that cannot arrive damaged. Check envelopes for financial correspondence. Coin envelopes for small parts and petty cash. Colored envelopes for direct mail campaigns. Self seal envelopes for volume mailing. All at all-sizes-envelopes.

24 lb wove stock on all standard commercial envelopes. Every blank commercial envelope at Business Envelopes is produced from 24 lb white wove stock, which exceeds the USPS minimum paper basis weight for letter-size mail and feeds reliably through postal sorting equipment.

Custom printed envelopes matched to your brand. Logo, return address, and brand colors printed directly on the envelope stock. PDF proof before production. Artwork on file for reorders. 7 to 10 business day turnaround. Available in #6 3/4, #9, #10, #11, 6 x 9, 9 x 12, and 10 x 13 formats.

Colored envelopes for campaigns where the outer envelope matters. Wove solid-color and starburst pattern formats in five sizes. For holiday card programs, fundraising appeals, and event invitations where the envelope creates the first impression, color does work that plain white stock cannot.

Trusted since 1997, free shipping on every order. No minimums on any product. Blank stock ships same or next business day. Custom printed stock ships 7 to 10 business days from proof approval. Free ground shipping to the contiguous 48 states on every order.

The bottom line on paper weight and thickness

Use lb for comparing within the same paper category. Use GSM for comparing across categories. Use pt for physical thickness, especially for direct mail compliance.

20 lb bond is copy paper. 24 lb bond is professional letterhead. 80 lb cover handles most cardstock print needs. 14 pt is the direct mail and business card commercial standard.

For USPS compliance, 14 pt commercial cardstock processes cleanly through every postal class relevant to direct mail. For letterhead, 24 lb bond in a #10 envelope is the correct pairing for standard First-Class letter mail. For documents that cannot be folded, clasp envelopes and Tyvek envelopes are the right format choices. For campaigns where the outer envelope creates the first impression, colored envelopes and custom printed envelopes carry the brand from the moment the piece arrives.

Frequently asked questions 

Why do two papers with the same lb number feel completely different?
Because they belong to different paper categories measured on different parent sheet sizes. An 80 lb text sheet uses a 25 x 38 inch parent. An 80 lb cover sheet uses a 20 x 26 inch parent. Use GSM to compare papers accurately across categories.

What is the difference between text weight and cover weight?
Text weight is lighter and more flexible, used for brochure interiors, book pages, and flyers. Cover weight is heavier and more rigid, used for business cards, postcards, greeting cards, and anything that needs to hold its shape. Text weight should not be used for pieces mailed without an envelope.

What paper weight should I use for professional letterhead?
24 lb bond (90 gsm) is the professional standard. It feeds through standard office printers and presents more substantially than 20 lb copy paper. 28 lb bond (105 gsm) is the premium choice for firms where paper quality is part of the brand.

What paper weight does USPS require for postcards?
USPS requires a minimum paper basis weight equivalent to approximately 80 lb cover and minimum thickness of 0.007 inch. Standard 14 pt commercial cardstock at 0.014 inch meets both requirements comfortably.

What does pt mean on paper?
Points measure physical thickness. One point equals 0.001 inch. A 14 pt sheet is 0.014 inches thick. Points are used primarily for cardstock in direct mail and commercial printing contexts.

How do I convert GSM to lb?
For text paper: divide GSM by 1.48. For cover paper: divide GSM by 2.71. These are estimates because actual caliper varies by mill and finish.

What envelope goes with 24 lb bond letterhead?
A #10 envelope (4.125 x 9.5 inches). A single sheet of 24 lb bond folded in thirds fits with appropriate clearance and the assembled piece comes in just under one ounce.

What is the heaviest paper I can run through a standard office laser printer?
Most standard office laser printers handle up to 80 lb cover (216 gsm) through the standard paper tray. Stock at 100 lb cover (270 gsm) typically requires manual feed. 14 pt and 16 pt commercial cardstock generally requires commercial printing equipment.