Area: Letter ≈ 0.0603 m² | A4 ≈ 0.0624 m² (A4 is 0.8% larger in area)
Key difference: Letter is 6 mm wider, A4 is 18 mm taller. Perfect for international document exchange.
1 Letter ≈ 0.967 A4 · 1 A4 ≈ 1.034 LetterLetter and A4 are very similar in size — just a 0.8% area difference.
📄 What is US Letter Paper Size?
Letter is the standard paper size used in the United States, Canada, Mexico, and several other countries. Its dimensions are 215.9 × 279.4 mm (8.5 × 11 inches), with an area of approximately 0.0603 m². Letter is the most common paper size in North America, used for everything from business correspondence to school reports and legal documents. It's also the default size for most home and office printers in the US.
📐 What is A4 Paper Size?
A4 is the international standard paper size used in almost every country outside North America. Its dimensions are 210 × 297 mm (8.27 × 11.69 inches), with an area of 0.0624 m². A4 is the most common paper size globally, used for letters, forms, reports, and everyday printing. It's part of the ISO 216 A-series, which is based on the √2 aspect ratio for consistent scaling.
🧮 The Math: Letter vs A4
Letter and A4 are very close in size but have different proportions. Here's how they compare:
- Width: Letter is 215.9 mm, A4 is 210 mm (Letter is 5.9 mm wider)
- Height: Letter is 279.4 mm, A4 is 297 mm (A4 is 17.6 mm taller)
- Area: Letter ≈ 0.0603 m², A4 ≈ 0.0624 m² (A4 is 0.8% larger)
- Aspect Ratio: Letter = 1.294:1, A4 = 1.414:1 (√2)
Conversion formulas:
- Letter → A4: A4 pages = Letter pages × 0.967 (area ratio)
- A4 → Letter: Letter pages = A4 pages × 1.034 (area ratio)
For practical purposes, 1 Letter page ≈ 1 A4 page — they're close enough that most documents fit both sizes with minimal adjustment.
📊 Quick Conversion Table: Letter to A4
| Letter Pages | A4 Equivalent | Area Difference | Real‑world use |
|---|---|---|---|
| 0.5 Letter | 0.48 A4 | −0.4% | Half-page document |
| 1 Letter | 0.97 A4 | −0.8% | Standard document |
| 2 Letter | 1.93 A4 | −0.8% | Two-page document |
| 5 Letter | 4.84 A4 | −0.8% | Short report |
| 10 Letter | 9.67 A4 | −0.8% | Report or proposal |
| 25 Letter | 24.18 A4 | −0.8% | Book chapter |
| 50 Letter | 48.35 A4 | −0.8% | Short book |
| 100 Letter | 96.70 A4 | −0.8% | Book or manual |
🌍 Real‑World Examples: Letter to A4 in Action
- 📄 International Business Communication: When sending documents between US and international offices, you need to convert Letter to A4. This tool helps you understand the sizing difference.
- 🖨️ Printing Across Borders: US documents printed on A4 paper will have slightly different margins. This converter helps you plan your layouts accordingly.
- 📚 Book Publishing: Books printed in both US and international markets need to account for the Letter vs A4 difference. This tool helps with page count planning.
- 📧 Digital Document Exchange: PDFs created in Letter format viewed on A4 screens will appear slightly different. Understanding the ratio helps with design.
- 📋 Forms and Applications: Many international forms are designed for A4. US users need to know how their Letter documents compare.
💡 Professional Tips for Letter to A4 Conversion
📐 Margin Adjustment
When converting Letter to A4, adjust margins: A4 is taller and narrower. Increase top/bottom margins by 3-4 mm and reduce left/right margins by 3 mm for best results.
🖨️ Printer Settings
Most modern printers support both Letter and A4. Always check your printer settings before printing international documents. Use "Scale to Fit" for automatic adjustment.
📄 PDF Creation
When creating PDFs, choose the correct page size. A PDF created in Letter will display differently on A4 screens. Use this converter to decide which size to use.
❓ Frequently Asked Questions (Letter to A4)
Q: Is Letter the same as A4?
A: No, they are different. Letter is 215.9 × 279.4 mm (8.5 × 11 in) and A4 is 210 × 297 mm (8.27 × 11.69 in). They are similar but not identical.
Q: Which is bigger, Letter or A4?
A: A4 is 0.8% larger in area. Letter is 6 mm wider, but A4 is 18 mm taller.
Q: Can I print Letter on A4?
A: Yes, most printers have a "scale to fit" option. However, the document may be slightly cropped or have extra margins.
Q: Can I print A4 on Letter?
A: Yes, but the document will be slightly smaller or have white space. Use "scale to fit" for best results.
Q: Why does the US use Letter instead of A4?
A: Historical reasons. Letter was standardized in the US in the 1920s, while the ISO 216 standard (including A4) was adopted internationally later. The US hasn't switched due to the cost and effort involved.
Q: What is the aspect ratio of Letter?
A: Letter has an aspect ratio of 1.294:1, while A4 has 1.414:1 (√2).
Q: How do I convert a Letter document to A4?
A: Use this converter to understand the size difference. In software like Word or PDF editors, you can change the page size and adjust margins.
Q: What is the difference in pixels at 300 DPI?
A: Letter at 300 DPI = 2550 × 3300 pixels. A4 at 300 DPI = 2480 × 3508 pixels. A4 has 80 more pixels in height, Letter has 70 more in width.
📈 Why Accurate Letter-to-A4 Conversion Matters
With global business becoming increasingly international, understanding the difference between Letter and A4 is essential. Whether you're sending documents abroad, printing international materials, or working with global partners, this tool ensures your documents look professional everywhere.
🌐 Global Standards & Localized Support
Letter is used primarily in the US, Canada, Mexico, and the Philippines. A4 is used in almost every other country. This tool bridges the gap between these two standards, making international document exchange seamless.
📐 The Full US & International Paper Size Comparison
- Letter = 215.9 × 279.4 mm (8.5 × 11 in) – US standard
- Legal = 215.9 × 355.6 mm (8.5 × 14 in) – US legal documents
- A4 = 210 × 297 mm (8.27 × 11.69 in) – International standard
- A3 = 297 × 420 mm (11.69 × 16.54 in) – International large format
- Tabloid / Ledger = 279.4 × 431.8 mm (11 × 17 in) – US large format
Understanding these sizes helps with international printing, document design, and global communication.
🔗 Explore More Paper & Print Tools
Check out our other converters: A4 to Letter, Letter to Legal, Legal to A4, A3 to A4, A4 to A3, PX to MM, and DPI Calculator. All designed to make your print and design workflows smoother.