A4 vs US Letter vs Legal Page Sizes
Exact dimensions, word capacity, regional usage, and which page size to choose for every document type.
TL;DR — Key Points
At a Glance
| Criterion | A4 | US Letter | US Legal |
|---|---|---|---|
| Width × Height (mm) | 210 × 297 mm | 215.9 × 279.4 mm | 215.9 × 355.6 mm |
| Width × Height (in) | 8.27 × 11.69 in | 8.5 × 11 in | 8.5 × 14 in |
| Pixels at 96 DPI | 794 × 1123 px | 816 × 1056 px | 816 × 1344 px |
| Pixels at 300 DPI | 2480 × 3508 px | 2550 × 3300 px | 2550 × 4200 px |
| Area | 623.7 cm² | 603.2 cm² | 767.7 cm² |
| Aspect ratio | 1:1.4142 (1:√2) | 1:1.2941 | 1:1.6471 |
| ISO 216 series | Yes — A4 | No — ANSI B | No — ANSI |
| Regional default | 200+ countries | US, Canada, Mexico | US legal/court use |
| Words/page (12pt SS) | ~500–520 | ~480–500 | ~620–660 |
| Words/page (12pt DS) | ~260–270 | ~250–260 | ~310–330 |
| Common uses | Academic, business, printing worldwide | US offices, schools, home printing | US contracts, court filings |
ISO 216 A-Series in Context
Every A-series size is exactly half the area of the previous one and shares the same 1:√2 aspect ratio — fold in half to get the next size.
| Size | Millimetres | Inches |
|---|---|---|
| A0 | 841 × 1189 mm | 33.1 × 46.8 in |
| A1 | 594 × 841 mm | 23.4 × 33.1 in |
| A2 | 420 × 594 mm | 16.5 × 23.4 in |
| A3 | 297 × 420 mm | 11.7 × 16.5 in |
| A4 | 210 × 297 mm | 8.27 × 11.69 in |
| A5 | 148 × 210 mm | 5.83 × 8.27 in |
| A6 | 105 × 148 mm | 4.13 × 5.83 in |
| Letter | 215.9 × 279.4 mm | 8.5 × 11 in |
| Legal | 215.9 × 355.6 mm | 8.5 × 14 in |
| Tabloid/Ledger | 279.4 × 431.8 mm | 11 × 17 in |
Quick Decision Guide
Use A4 when…
- Any document for a non-US, non-Canadian, non-Mexican recipient
- Academic papers submitted to international journals
- CVs and cover letters sent to European, Asian, or Indian employers
- PDFs shared globally — safest default outside North America
- Documents printed on office printers in India, UK, Europe, or Australia
- ISO-compliant technical documentation
Use US Letter when…
- US school and college assignments (unless A4 is specified)
- Documents printed on US office printers
- US business correspondence, invoices, and proposals
- Resumes and cover letters for US job applications
- Any document primarily for US or Canadian recipients
Use US Legal when…
- US contracts, deeds, wills, and trust documents
- US court filings that require Legal size (check court rules)
- Notarised documents with multiple signature blocks
- Blueprints or technical specs that need extra vertical length
- Any document prepared by or for a US legal professional
Deep Dive
A4 (ISO 216)
A4 (210 × 297 mm) is part of the ISO 216 standard, derived from a German DIN standard first published in 1922 and adopted internationally in 1975. The defining property of the A-series is that every sheet has a width-to-height ratio of 1:√2 (approximately 1:1.4142). This means that folding an A4 sheet in half along its longer dimension produces two A5 sheets — each with the same 1:√2 aspect ratio. This self-similar property makes scaling between A-series sizes mathematically perfect: enlarging A5 to A4 is exactly 141% (√2 × 100%), with no distortion.
A4 is used for virtually all document printing, official correspondence, academic papers, and business communications in Europe, Asia, Africa, India, Australia, and most of South America. The A0 size (841 × 1189 mm) has an area of exactly 1 square metre — the entire A-series derives from this definition.
US Letter (ANSI A)
US Letter (8.5 × 11 inches = 215.9 × 279.4 mm) evolved from American paper-making traditions predating ISO standardisation. It is 0.23 inches (5.9 mm) wider than A4 and 0.69 inches (17.6 mm) shorter. The extra width means slightly more horizontal space per line; the reduced height means slightly fewer lines per page. Net result: approximately 2–4% fewer words per page than A4 at equivalent font and margins.
The US Letter standard is maintained by ANSI (American National Standards Institute) as ANSI A. The corresponding tabloid/ledger size is ANSI B (11 × 17 inches). Unlike ISO 216, ANSI sizes do not share the √2 aspect ratio property — scaling between ANSI sizes distorts content proportions.
US Legal
US Legal (8.5 × 14 inches = 215.9 × 355.6 mm) has the same width as US Letter but is 3 inches (76.2 mm) taller. The extra length dates from a time when legal documents required continuous text without page breaks at awkward points — long clauses, signature blocks, and exhibit attachments all benefited from the additional vertical space. Today, Legal paper is increasingly rare even in legal practice, as courts shift to Letter requirements and digital signatures eliminate the physical need for signature space. A Legal-size sheet is not part of the ISO 216 system and has no standard half-size equivalent used in practice.
Real-World Patterns
Academic and Scientific Publishing
International academic journals — including those published by Elsevier, Springer, Nature, and IEEE — use A4 for their print and PDF layouts. Submission guidelines almost universally specify A4 for manuscripts submitted outside the US. US journals (including many American university presses and society publications) use US Letter. If you are submitting an academic paper, check the journal's author guidelines for the specified page size. When in doubt, submit A4 — it is the global default and virtually all US publishers can accept it. For conference proceedings, check whether the venue is US-based (Letter) or international (A4).
Business Documents and Printing
In India, the UK, Europe, Singapore, and most of the world, office printers are loaded with A4 paper by default. Sending a US Letter PDF to a colleague in these regions causes the printer to either add white borders, scale down ~3%, or prompt for a paper size change. The reverse is equally common when a European colleague sends an A4 document to a US office. The practical solution: if your organisation operates across regions, standardise on A4 (the more globally common size) and specify actual-size printing. Alternatively, design with a 'safe zone' — keeping all content within the 8.27-inch width ensures the document prints correctly on both sizes without any content clipping.
Legal Practice in the US
US Legal paper (8.5 × 14 inches) persists specifically in legal practice. Many states require Legal-sized paper for certain filings — deed recordings, probate filings, and some court pleadings. However, federal courts (including the US Supreme Court and most US District Courts) now require Letter-sized documents. Law firms maintain both paper sizes. Legal-size file folders (14 inches deep) are standard in law office filing systems. A common mistake: printing a Letter-sized contract template on Legal paper, leaving 3 inches of blank space at the bottom — this is a formatting error that can make documents look unfinished. Match the template to the paper size.
Design and Print Production
Graphic designers and print production teams must specify the exact paper size and bleed settings for every project. For brochures, flyers, and marketing materials destined for US distribution: Letter or its half (5.5 × 8.5 in) is standard. For international distribution: A4 or A5. Printers specify bleed (usually 3mm / 0.125 in on all sides) beyond the trim size. A4 vs Letter matters at the imposition stage — fitting multiple pages on a press sheet depends on the sheet size, and European printing presses are often configured for ISO sizes. A US-sized document sent to a European print shop may require reformatting.
Which should you use?
A4 is the correct choice for any document shared internationally, submitted to a non-US institution, or printed outside North America. It is the global default. US Letter is the correct choice for documents intended for US or Canadian recipients, US academic submissions, and documents that will be printed on US office equipment.
US Legal has a narrow, specific use case: US legal practice — contracts, deeds, some court filings. Avoid it for general documents. If you're unsure and the document will reach both US and international recipients, design with conservative 1-inch margins and export as A4 — US printers can handle it with minimal or no scaling.
Decision Checklist
| Scenario | Use |
|---|---|
| Academic paper for a non-US journal | A4 |
| US college essay or assignment | US Letter |
| CV / resume for a UK or European employer | A4 |
| Resume for a US employer | US Letter |
| PDF shared with a global audience | A4 |
| US legal contract or deed | US Legal |
| Printing in India, UK, Europe, or Australia | A4 |
| Printing in the US or Canada | US Letter |
| Court filing in a US federal court | US Letter (check rules) |
| International conference paper submission | A4 |
| Marketing brochure for US distribution | US Letter |
| Invoice sent to a European client | A4 |
Frequently Asked Questions
What are the exact dimensions of A4, US Letter, and US Legal?
A4: 210 × 297 mm (8.27 × 11.69 inches). US Letter: 215.9 × 279.4 mm (8.5 × 11 inches). US Legal: 215.9 × 355.6 mm (8.5 × 14 inches). A4 is slightly narrower and taller than Letter. Legal has the same width as Letter but is 3 inches taller. At 96 DPI: A4 = 794 × 1123 px; Letter = 816 × 1056 px; Legal = 816 × 1344 px. At 300 DPI (print): A4 = 2480 × 3508 px; Letter = 2550 × 3300 px; Legal = 2550 × 4200 px.
Why does the US use Letter size instead of A4?
The US adopted its paper sizes before the ISO 216 standard (which defines A4) was developed. US Letter (8.5 × 11 inches) evolved from earlier American paper-making traditions and was standardised by the American National Standards Institute (ANSI). The ISO 216 A-series was standardised in 1975 based on a German DIN standard from 1922. Despite multiple attempts, the US, Canada, and Mexico never adopted ISO 216 for general use — partly due to the enormous cost of replacing existing infrastructure (filing cabinets, printers, form designs) and partly due to general resistance to metric standardisation.
Which countries use A4 and which use US Letter?
A4 is the standard in almost every country in the world — all of Europe, all of Asia, all of Africa, Australia, New Zealand, South America (except parts of Mexico), and India. US Letter is the standard in the United States, Canada, and Mexico. The Philippines officially moved to A4 for government documents in 2014, though Letter paper is still widely used there in practice. If you are printing a document for an international audience or submitting to a non-US institution, A4 is the correct choice.
What happens when you print an A4 document on US Letter paper or vice versa?
Printing A4 on Letter: A4 is taller (11.69 in vs 11 in) and narrower (8.27 in vs 8.5 in). If you print at 100% scale, the bottom 0.69 inches of content will be cut off or pushed onto the next page. Most printers and PDF viewers auto-scale to fit, which shrinks the content slightly (~97%). Printing Letter on A4: Letter is wider (8.5 in vs 8.27 in). The wider margins get clipped. The safest approach for cross-region documents is to always embed fonts, export as PDF with the intended page size, and specify 'actual size' (no scaling) when printing. Alternatively, design with conservative 1-inch margins — both sizes accommodate these without clipping.
What is US Legal paper used for?
US Legal (8.5 × 14 inches) is used primarily for legal documents in the United States: contracts, deeds, wills, pleadings, and court filings. The extra length (3 inches taller than Letter) historically provided space for longer paragraphs and signature blocks without page breaks at awkward positions. Many law firms and notary offices keep Legal-sized paper specifically for contracts. US Legal is increasingly rare in modern practice — many courts now accept or require Letter-sized documents, and digital signatures have reduced the need for physical signature space. Legal-sized file folders and cabinets are a separate standard from Letter-sized ones.
What is the ISO 216 paper size system?
ISO 216 defines the international A-series paper sizes based on a single elegant mathematical property: every size has an aspect ratio of 1:√2 (approximately 1:1.4142). This means when you cut or fold an A-series sheet in half along its longer dimension, you get the next smaller size with the same aspect ratio. A0 (841 × 1189 mm, area = 1 m²) → fold in half → A1 → A2 → A3 → A4 → A5 → A6, and so on. This property makes scaling between sizes perfect: an A4 document printed on A3 is exactly 141% (√2 × 100%) — no content is clipped or distorted. The US ANSI series (Letter, Legal, Ledger/Tabloid) does not share this property, making scaling between sizes more complex.
How many words fit on A4 vs US Letter per page?
With 1-inch margins, 12pt Times New Roman, single spacing: A4 fits approximately 500–520 words per page; US Letter fits approximately 480–500 words per page. A4 is slightly taller, giving it about 2–3 extra lines per page. The difference is small (roughly 3–5%) and imperceptible in most documents. Double-spaced: A4 ≈ 260–270 words/page; Letter ≈ 250–260 words/page. For practical purposes, word-per-page estimates are essentially the same — the size difference (0.69 inches in height) adds only about 2 lines of text at 12pt.
What page size should I use for a PDF sent internationally?
For documents sent to recipients in Europe, Asia, India, or Australia — use A4. For documents sent primarily to US or Canadian recipients — use Letter. For documents with a truly global audience, A4 is the safer choice because it is the global default and most international print services assume A4. If the recipient prints your Letter-sized PDF on A4 paper, the printer will auto-scale (typically to ~97%) or add small white borders — the content is readable but not at exact dimensions. Design with 1-inch margins on all sides to ensure safe printing on both sizes without content loss.
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Verdict: Choose Based On Your Situation
A4 (210×297 mm)
- You're in Europe, Asia, or most parts of the world
- You need ISO standard size for international consistency
- You're printing documents for global distribution
- You want optimal paper usage
US Letter (8.5×11 inches)
- You're in the United States or Canada
- You have legacy equipment designed for US sizes
- You're following US company standards
- You need compatibility with older office equipment
US Legal (8.5×14 inches)
- You need extra vertical space for legal documents
- You're in a legal or government context
- You need to avoid page breaks in longer documents
- Your organization mandates legal-size for records