What is the main difference between A4 and Letter paper?

The main difference is dimensions: A4 measures 210 x 297 mm (8.27 x 11.69 inches), while Letter measures 216 x 279 mm (8.5 x 11 inches), making A4 taller and narrower.

Is A4 paper the same size as US Letter paper?

No, A4 and Letter are not the same size; A4 is 6 mm narrower and 18 mm longer than Letter, so documents formatted for one will not print perfectly on the other.

Which paper size is better for printing documents, A4 or Letter?

Neither is universally better; A4 is the standard for international business and academic use, while Letter is the default for North American office and personal printing.

Does using Letter paper instead of A4 increase printing costs?

Yes, using Letter in A4-dominant regions can increase costs because it requires special ordering, higher per-sheet prices, and potential waste from trimming or reformatting documents.

Is there a risk of paper jams when mixing A4 and Letter paper?

Yes, mixing A4 and Letter in the same tray risks jams and misfeeds because the 6 mm width difference causes alignment issues with the printer’s paper guides and rollers.

Will A4 paper fit in a binder designed for Letter paper?

No, A4 paper will not fit properly in a Letter binder because the 18 mm extra length protrudes beyond the sleeve, causing bent corners and damage to the document.

What is the most common mistake beginners make with A4 and Letter sizes?

The most common mistake is assuming they are interchangeable, which leads to clipped margins, misaligned headers, and text cut off at the bottom of the page.

Can A4 and Letter paper be used interchangeably in the same printer?

Yes, most modern printers can handle both A4 and Letter, but you must adjust the tray guides and select the correct paper size in the print settings for each job.

Why do US companies use Letter paper while the rest of the world uses A4?

US companies use Letter because of historical standardization on imperial measurements, while the rest of the world adopted A4 as part of the metric ISO 216 standard for efficiency.

Can I switch from Letter to A4 without changing my document layout?

No, you cannot switch without layout changes because the aspect ratios differ, so you must adjust margins, font sizes, and image placements to avoid white space or cropping.

Difference Between

Difference Between A4 and Letter

Written byNex Virox Team

Editorial Team

Reviewed byVarshal Nirbhavane

Senior SEO & Organic Growth Professional · 5+ years

Published: September 6, 202618 min read

Quick answer

The main difference between A4 and Letter is that A4 is 210 × 297 mm (8.27 × 11.69 inches), while Letter is 8.5 × 11 inches (215.9 × 279.4 mm). A4 is the international standard used globally, while Letter is the US and Canada standard.

Key takeaways

Core distinction: A4 measures 210 x 297 mm while Letter is 8.5 x 11 inches (216 x 279 mm).
How each works: A4 is taller and narrower, while Letter is shorter and wider, affecting margins.
Cost and effort: Mixing both paper sizes causes printing errors, wasted sheets, and formatting adjustments.
Best-fit use case: A4 dominates globally except North America, where Letter remains the standard.
Common decision mistake: Assuming digital documents auto-resize correctly when switching between A4 and Letter.

Table of Contents18 sections

Difference Between A4 and Letter: Comparison Table

Aspect	A4	Letter
Definition	International standard paper size measuring 210 × 297 millimeters.	North American paper size measuring 8.5 × 11 inches (216 × 279 mm).
Purpose	Designed for global business, academic, and government documentation.	Built for US and Canadian business correspondence and printing.
Core Mechanism	Derived from ISO 216 standard with √2 aspect ratio.	Based on customary US inch measurements, not a mathematical ratio.
Width	Spans 210 millimeters, roughly 6 millimeters narrower than Letter.	Measures 216 millimeters, about 6 millimeters wider than A4.
Height	Reaches 297 millimeters, approximately 18 millimeters taller than Letter.	Stands 279 millimeters, roughly 18 millimeters shorter than A4.
Aspect Ratio	Maintains a precise 1:1.414 ratio, allowing uniform scaling.	Uses a 1:1.294 ratio, which distorts when scaled to A4.
Area	Covers 62,370 square millimeters of printable surface.	Spans 60,264 square millimeters, about 3.4% less area.
Scaling	Scales perfectly to A5, A3, and other A-series sizes.	Requires cropping or distortion when converting to A-series.
Origin	Adopted from German DIN 476 standard in 1922.	Evolved from early US paper sizes, standardized in the 1920s.
Governing Body	Regulated by ISO 216, recognized in 148 countries.	Defined by ANSI/ASME Y14.1, used mainly in North America.
Global Usage	Dominates all continents except North America.	Standard in the United States, Canada, Mexico, and Philippines.
Print Compatibility	Fits most international printers with universal paper trays.	Requires US-spec printers or manual tray adjustment elsewhere.
Document Margins	Offers narrower width but taller vertical writing space.	Provides wider horizontal space for charts and tables.
Word Processing	Default page size in Microsoft Word outside North America.	Default page size in Microsoft Word for US and Canada.
Filing Systems	Fits international ring binders and lever-arch files.	Matches US 3-ring binders and standard file folders.
Envelope Fit	Pairs with C4 envelopes measuring 229 × 324 millimeters.	Slides into #10 envelopes sized 4.125 × 9.5 inches.
Copy Paper Cost	Priced per ream in metric-based markets, often cheaper globally.	Priced per ream in US markets, subject to local commodity rates.
Print Speed	Feeds through printers at same speed as Letter in modern devices.	Prints at identical speed to A4 in dual-standard machines.
Ink Coverage	Uses slightly more ink per page due to 3.4% larger area.	Requires marginally less ink, saving cost on high-volume printing.
Accuracy	Offers metric precision to the nearest millimeter.	Uses imperial fractions, accurate to 0.5 inch increments.
Durability	Standard 80 gsm weight provides consistent archival quality.	Common 20 lb bond weight equals 75 gsm, slightly lighter.
Scalability	Scales to A0 posters and A6 cards without ratio distortion.	Scales poorly to larger formats like ledger or tabloid.
Maintenance	Requires no special handling in metric-based print shops.	Needs dedicated trays in regions where A4 is standard.
Safety Standards	Complies with EU packaging and forestry regulations.	Meets US CPSIA and forest stewardship council requirements.
Software Default	Set as default in Google Docs for non-US locales.	Set as default in Google Docs for US and Canadian users.
Availability	Found in virtually every stationery store outside the Americas.	Readily stocked in US office supply chains and supermarkets.
Common Examples	Used for European academic papers, UK legal filings, and EU reports.	Used for US resumes, American contracts, and Canadian memos.
Typical Users	Students, researchers, and businesses across 148 countries.	US office workers, American students, and Canadian firms.
Limitations	Feels narrow for wide spreadsheets and landscape presentations.	Fails to match international submission requirements abroad.
Best-Fit Scenario	Choose for global publishing, EU submissions, or metric workflows.	Choose for US domestic printing, American forms, or inch-based work.

What Is A4?

A4 is the international standard paper size measuring 210 by 297 millimeters. It is the default paper format in nearly every country except the United States and Canada. A4 exists to provide a consistent, globally recognised sheet size for printing, copying and official documentation.

Definition of A4

A4 is a rectangular paper dimension defined by ISO 216, with a width of 210 millimeters and a height of 297 millimeters. Its aspect ratio is the square root of two, allowing it to scale perfectly between sizes in the A-series. This ratio ensures that halving a sheet produces two identical smaller sheets.

Key Characteristics of A4

Characteristic	What It Means in Practice
210 x 297 mm	A4 is 8.27 inches wide and 11.69 inches tall, making it taller and narrower than US Letter.
ISO 216 standard	A4 follows the international standard used by 148 countries across Europe, Asia, Africa and Oceania.
Square-root ratio	Each A-series size is half the previous one, so A4 folds cleanly into A5 without wasted margin.
Global default	Printers, copiers and software in most of the world ship with A4 as the preset paper size.
Metric measurement	A4 uses millimetres as its official unit, aligning with the metric system used in most nations.
Weight in gsm	Standard A4 office paper is 80 gsm, though 75 gsm and 100 gsm variants are also common.
Universal tray fit	Most international printers and multifunction devices are engineered specifically for A4 dimensions.
Document standard	Government forms, academic papers and legal contracts in non-US countries default to A4 format.
Envelope compatibility	A4 fits standard C4 envelopes without folding, and folds once to fit DL envelopes for mailing.
Digital default	Word processors and PDF creators in most regions set A4 as the automatic page size for new files.

Common Examples of A4

European CV - A4 is the mandatory format for job applications across the EU, UK and Australia.
University dissertations - Most international universities require A4 paper for thesis submission and printing.
UK government forms - HM Revenue and Customs tax returns are printed exclusively on A4 sheets.
German contracts - German business and legal agreements are standardised on A4 for archival consistency.
Japanese office documents - Japanese corporations use A4 as the default for internal memos and reports.
International airline tickets - E-ticket confirmations and boarding passes print on A4 in most global carriers.
Chinese regulatory filings - Chinese company registration documents require A4 paper for official submission.
French administrative forms - French public services issue all official paperwork on A4 format.
Indian academic certificates - Indian universities and examination boards print mark sheets on A4.
Australian medical records - Australian healthcare providers standardise patient files on A4 paper.

Advantages and Limitations of A4

Advantages	Limitations
A4 is the global standard, so documents transfer seamlessly across borders and international businesses.	A4 is 6 millimetres narrower than US Letter, causing formatting problems when printing US-designed files.
The square-root aspect ratio means scaling between A4, A3 and A5 is mathematically perfect and lossless.	A4 is 18 millimetres taller than Letter, which can cut off content when printing documents built for American paper.
A4 is universally available in every country except the US and Canada, so sourcing paper is never an issue.	US printers and software often lack A4 presets, forcing manual custom size setup for international users.
A4 aligns with the metric system, making measurements straightforward for engineers and scientists worldwide.	A4 does not fit US ring binders and folders, which are engineered for the shorter Letter dimension.
International publishers and journals accept A4 as the default manuscript format without special instructions.	A4 is not the standard in North America, so US colleagues may struggle to print or file A4 documents correctly.
A4 envelopes and filing systems are standardised, making storage and mailing efficient across most of the world.	The taller aspect ratio can make A4 documents feel awkward when viewed side-by-side with US Letter pages.
A4 photocopiers and multifunction devices are cheaper and more varied in international markets due to high demand.	Converting a Letter document to A4 often requires scaling, which can shrink text to an uncomfortable reading size.
A4 is the required format for international standards bodies, patents and EU regulatory submissions.	A4 is rarely stocked in US office supply stores, forcing special orders for expatriates and global teams.
A4 paper is manufactured to tight ISO tolerances, ensuring consistent quality across different brands and mills.	A4's narrower width means charts, tables and wide spreadsheets often need landscape orientation to fit properly.
A4 is the default in all major word processors when the language is set to a non-US locale.	A4 is incompatible with US filing cabinets and archival boxes designed specifically for Letter dimensions.

What Is Letter?

Letter is the standard North American paper size, measuring 8.5 by 11 inches. It is the default format for business documents, school assignments, and personal printing across the United States and Canada. Letter exists because imperial measurements and regional printing traditions shaped a distinct standard.

Definition of Letter

Letter is a paper dimension defined by ANSI standard ASME Y14.1, with a width of 215.9 millimeters and a height of 279.4 millimeters. It is the nominal size for office printers, copiers, and filing systems in the United States and Canada. Its aspect ratio is approximately 1:1.294.

Key Characteristics of Letter

Characteristic	What It Means in Practice
Exact dimensions	Measures 8.5 inches wide by 11 inches tall, or 215.9 by 279.4 millimeters.
Imperial origin	Derived from US customary units, unlike A4 which uses the metric system.
Regional dominance	Standard in the US, Canada, Mexico, the Philippines, and several Latin American nations.
Wider profile	Is 6 millimeters wider than A4, giving more horizontal space for charts and tables.
Shorter height	Is 18 millimeters shorter than A4, which reduces vertical space for long paragraphs.
Printer default	Most US-market printers ship preconfigured with Letter as the factory default tray setting.
Filing compatibility	Fits standard US manila folders, three-ring binders, and filing cabinets without trimming.
Weight convention	Bond paper is commonly sold in 20-pound or 24-pound weights, affecting opacity and stiffness.
No aspect ratio	Lacks the consistent 1:√2 ratio of A4, so scaling between sizes requires cropping or margins.
Envelope pairing	Folds cleanly to fit the standard #10 business envelope, the most common US mailing size.

Common Examples of Letter

US tax returns – IRS Form 1040 is printed exclusively on Letter paper for filing and archival.
Resumes – American job seekers submit resumes on Letter because recruiters expect this exact size.
Legal contracts – US law firms draft agreements on Letter, aligning with court filing requirements.
Academic transcripts – US universities issue official transcripts on Letter for admissions and employers.
Medical records – HIPAA-compliant patient charts use Letter for standardized storage in US clinics.
Newspaper inserts – US retail flyers and coupons are cut to Letter for easy insertion into dailies.
Government forms – Passport applications and Social Security documents use Letter exclusively.
Manuals – US consumer electronics include Letter-sized quick-start guides in retail packaging.
Insurance policies – US auto and home insurers print policy declarations on Letter for state compliance.
Bank statements – US financial institutions mail monthly statements on Letter for envelope compatibility.

Advantages and Limitations of Letter

Advantages	Limitations
Native fit for US printers, copiers, and scanners without manual size selection.	Rejected by international journals and conferences that mandate A4 submissions.
Wider width suits landscape-oriented tables, spreadsheets, and financial charts.	Shorter height causes more page breaks in text-heavy documents compared to A4.
Universal availability in US office supply stores at the lowest per-sheet cost.	Scaling to A4 distorts margins and often cuts off content when printing abroad.
Compatible with #10 envelopes, reducing postage costs for standard business mail.	Filing systems in Europe and Asia cannot store Letter sheets without folding.
Strong US legal precedent in court filing formats and notarization standards.	Digital PDFs created for Letter display awkward white bars on A4 screens.
Wider margins allow comfortable annotation space for handwritten edits.	Photocopying an A4 original onto Letter crops the top and bottom lines.
Backed by ANSI standards, ensuring consistent quality across US manufacturers.	No logical scaling relationship with legal size, tabloid, or other US variants.
Lighter weight variants reduce shipping costs for bulk US mail campaigns.	International clients often misprint Letter documents because their software defaults to A4.
Standardized three-hole punching fits ubiquitous US ring binders.	Book publishers avoid Letter because its ratio does not match common trim sizes.
Familiarity reduces user error in US offices where every device expects this size.	Global supply chains frequently backorder Letter stock, delaying US print jobs.

Similarities Between A4 and Letter

Shared Aspect	How A4 and Letter Are Alike
Paper category	A4 and Letter are both cut-size office papers designed for everyday printing and copying tasks.
Primary purpose	A4 and Letter both serve as standard media for documents, correspondence, and business communication.
Sheet basis	A4 and Letter are both sold as individual sheets rather than continuous rolls or large format stock.
Standard weight	A4 and Letter both commonly come in 80 gsm or 20 lb bond weight for general use.
Brightness level	A4 and Letter both typically offer 92-96 brightness for crisp text and clear image reproduction.
Opacity range	A4 and Letter both provide sufficient opacity to prevent text show-through on double-sided printing.
Color options	A4 and Letter both come in white as default, plus pastel and bright color assortments.
Finish type	A4 and Letter both offer uncoated, matte, and glossy finishes for different print jobs.
Printer support	A4 and Letter both feed through virtually all modern laser and inkjet printers.
Copier compatibility	A4 and Letter both work in standard office copiers and multifunction devices without adjustment.
Scanner input	A4 and Letter both fit flatbed scanners and automatic document feeders for digitization.
Filing system	A4 and Letter both punch cleanly into standard ring binders and lever-arch files.
Envelope fit	A4 and Letter both fold neatly to fit common business envelopes like DL and #10 sizes.
Packaging unit	A4 and Letter both ship in reams of 500 sheets and cartons of 5 or 10 reams.
Retail price	A4 and Letter both cost roughly the same per ream, with no significant price premium.
Recyclability	A4 and Letter both recycle through standard mixed-paper streams at office facilities.
Environmental cert	A4 and Letter both carry FSC or PEFC chain-of-custody certification options.
Storage needs	A4 and Letter both require flat, dry storage to avoid curling and moisture damage.
Shelf life	A4 and Letter both remain printable for years when kept sealed and away from sunlight.
Print quality	A4 and Letter both produce sharp text and vibrant graphics at 600 dpi or higher.
Drying speed	A4 and Letter both accept ink quickly, preventing smudging on standard office printers.
Folding ease	A4 and Letter both crease cleanly for brochures, letters, and tri-fold mailers.
Cutting ease	A4 and Letter both trim cleanly with guillotine cutters or scissors without fraying.
Writing surface	A4 and Letter both accept pen, pencil, and marker without bleed-through on typical weights.
User base	A4 and Letter both serve students, home offices, and corporate workplaces every day.
Global reach	A4 and Letter both appear in international markets, though regional preference differs.
Software default	A4 and Letter both appear as preset page sizes in Microsoft Word and Google Docs.
Print driver	A4 and Letter both auto-select correctly via most printer drivers based on document settings.
Waste risk	A4 and Letter both jam or misfeed if exposed to humidity, dust, or bent corners.
Long-term use	A4 and Letter both remain archival-safe with acid-free options for permanent records.

A4 or Letter: Which Should You Choose?

Choose the paper size that matches your geographic market. If you print, mail, or file documents for recipients in North America, Letter is the standard. If your audience is anywhere else in the world, A4 is the default. This one variable—your reader's location—decides it for most people.

When to Use A4

Choose A4 when your documents cross international borders. Use it for global business correspondence, European government forms, or academic submissions to non-US journals. It also suits metric-system workflows where software defaults, printers, and filing systems are calibrated to 210 x 297 mm dimensions.

When to Use Letter

Choose Letter when your entire workflow stays within the United States or Canada. Use it for domestic legal filings, US government forms, and standard office printing. It also fits North American filing cabinets and binders, which are manufactured to hold the 8.5 x 11 inch sheet size.

Common Misconceptions About A4 and Letter

Common Myth	The Reality
A4 and Letter paper are the exact same size.	A4 is 210 x 297 mm, while Letter is 216 x 279 mm, making A4 taller and Letter wider.
Letter paper is just the American name for A4.	Letter is a distinct North American standard, and A4 is the international ISO 216 standard used globally.
The 6-millimeter difference between A4 and Letter never matters.	The 6 mm width difference causes misaligned margins, cut-off text, and formatting errors when printing documents across standards.
A4 paper is slightly larger than Letter paper in every dimension.	A4 is 6 mm narrower but 18 mm longer than Letter, so neither sheet is universally larger.
Printers automatically adjust paper size settings for A4 or Letter.	Printers require manual tray and driver settings, and auto-detection fails when both paper types are loaded.
You can mix A4 and Letter in the same document without issues.	Mixing A4 and Letter in one file shifts page breaks and pagination, causing inconsistent print output.
A4 is the standard paper size used in the United States.	The United States primarily uses Letter, while A4 is the standard in nearly every other country worldwide.
Letter paper is based on the metric system like A4.	Letter is based on imperial inches (8.5 x 11), while A4 is derived from the metric ISO 216 standard.
Scaling A4 to Letter or vice versa keeps the layout intact.	Scaling changes font sizes and image dimensions, so scaled documents look smaller or larger than the original design.
A4 and Letter paper have the same aspect ratio.	A4 has a 1:1.414 aspect ratio, while Letter has a 1:1.294 ratio, so shapes do not map proportionally.
Envelopes designed for Letter also fit A4 paper perfectly.	A4 is longer, so it protrudes from Letter-sized envelopes, and A4 envelopes are too loose for Letter sheets.
Binders and folders labeled A4 work fine with Letter paper.	Letter paper is wider, so it sticks out of A4 binders, and A4 sheets rattle loosely inside Letter folders.
Most software defaults to the correct paper size automatically.	Software defaults follow the regional locale, so US software uses Letter and international software uses A4.
PDF files display identically on screen regardless of paper size.	PDFs embed page dimensions, so A4 and Letter PDFs render with different on-screen zoom and print sizes.
Copying an A4 document onto Letter paper requires no adjustment.	Copiers shrink or crop content by default, and manual zoom settings are needed to avoid cut-off edges.
A4 paper is thicker and heavier than Letter paper.	Paper weight is independent of size, so A4 and Letter both come in 80 gsm, 100 gsm, and other weights.
Letter paper is used only in the USA and nowhere else.	Letter is also standard in Canada, Mexico, the Philippines, and several Latin American countries.
A4 is the legal standard for all government documents.	US government agencies use Letter, while A4 is the legal standard for governments in most other nations.
You can fold A4 to match Letter dimensions without losing content.	Folding A4 creates a crease that damages the document and still leaves a width mismatch with Letter.
Printers with a universal tray accept A4 and Letter interchangeably.	Universal trays hold both sizes, but the paper guides must be adjusted or misalignment and jams occur.
The difference between A4 and Letter is purely cosmetic.	The size difference causes real functional problems in printing, binding, filing, and document exchange.
All international journals and publishers accept Letter paper.	Most international journals require A4, and Letter submissions are often rejected or returned for reformatting.
A4 paper fits perfectly into standard three-ring binders.	Standard US three-ring binders are sized for Letter, so A4 sheets overhang the edges of the binder.
Letter paper is the same as the old British Imperial foolscap size.	Foolscap is 203 x 330 mm, which is narrower and much longer than Letter, so the two are not equivalent.
Changing the paper size in print settings fixes all A4 and Letter issues.	Print settings must match the document page setup, or the printer clips content or adds blank margins.
A4 and Letter are the only two paper sizes that matter.	Legal (8.5 x 14), Tabloid (11 x 17), and A3 (297 x 420) are also common, and each has distinct uses.
Scanners can digitize A4 and Letter documents at the same resolution.	Scanners output different pixel counts for each size at a given DPI, so A4 scans produce more pixels.
You can buy A4 paper in any US office supply store.	US stores stock A4 mainly in specialty sections, while Letter dominates shelves and is far easier to find.
Letter paper is the metric equivalent of A4 rounded to inches.	Letter is an independent ANSI standard, and its 8.5 x 11-inch dimensions do not derive from A4 measurements.
Converting a Word document from A4 to Letter preserves all formatting.	Converting changes margins, tab stops, and image placement, so Word documents require manual layout review.

Conclusion

Difference Between A4 and Letter comes down to dimensions: A4 is taller and narrower at 210×297 mm, while Letter is shorter and wider at 8.5×11 inches. Choose A4 for international use, Letter for North American printing.

FAQs on Difference Between A4 and Letter

What is the main difference between A4 and Letter paper?: The main difference is dimensions: A4 measures 210 x 297 mm (8.27 x 11.69 inches), while Letter measures 216 x 279 mm (8.5 x 11 inches), making A4 taller and narrower.
Is A4 paper the same size as US Letter paper?: No, A4 and Letter are not the same size; A4 is 6 mm narrower and 18 mm longer than Letter, so documents formatted for one will not print perfectly on the other.
Which paper size is better for printing documents, A4 or Letter?: Neither is universally better; A4 is the standard for international business and academic use, while Letter is the default for North American office and personal printing.
Does using Letter paper instead of A4 increase printing costs?: Yes, using Letter in A4-dominant regions can increase costs because it requires special ordering, higher per-sheet prices, and potential waste from trimming or reformatting documents.
Is there a risk of paper jams when mixing A4 and Letter paper?: Yes, mixing A4 and Letter in the same tray risks jams and misfeeds because the 6 mm width difference causes alignment issues with the printer’s paper guides and rollers.
Will A4 paper fit in a binder designed for Letter paper?: No, A4 paper will not fit properly in a Letter binder because the 18 mm extra length protrudes beyond the sleeve, causing bent corners and damage to the document.
What is the most common mistake beginners make with A4 and Letter sizes?: The most common mistake is assuming they are interchangeable, which leads to clipped margins, misaligned headers, and text cut off at the bottom of the page.
Can A4 and Letter paper be used interchangeably in the same printer?: Yes, most modern printers can handle both A4 and Letter, but you must adjust the tray guides and select the correct paper size in the print settings for each job.
Why do US companies use Letter paper while the rest of the world uses A4?: US companies use Letter because of historical standardization on imperial measurements, while the rest of the world adopted A4 as part of the metric ISO 216 standard for efficiency.
Can I switch from Letter to A4 without changing my document layout?: No, you cannot switch without layout changes because the aspect ratios differ, so you must adjust margins, font sizes, and image placements to avoid white space or cropping.