Understand the difference between A4, Letter, Legal, and other paper sizes, and learn which format to use for documents, photos, and presentations.
Step-by-Step Guide
Know the Two Main Standards
The world uses two primary paper-size systems. The ISO 216 standard (A-series) is used in almost every country: A4 (210 × 297 mm) is the default for documents. North America uses its own system: Letter (8.5 × 11 in / 216 × 279 mm) is the equivalent default.
Understand the A-Series Logic
Each A-size is exactly half the previous one: A3 folded in half = A4; A4 folded = A5. This makes scaling perfectly proportional. A0 is the base size (1 m²). A4 is used for letters and documents, A3 for posters and spreadsheets, A5 for notebooks and flyers.
Common Use Cases by Size
A4 / Letter → standard documents, CVs, contracts | A3 / Tabloid (11×17 in) → posters, diagrams, newspapers | A5 → notebooks, half-fold brochures | A6 → postcards | Legal (8.5×14 in) → legal contracts in the US | B5 → books and some magazines.
Check Your Printer Settings
Before printing, confirm that the paper size in your printer settings matches the actual paper loaded. A mismatch causes cropped output or unwanted white borders. In most apps: File → Print → Paper Size.
Handle A4 vs Letter Differences
A4 is slightly taller and narrower than Letter. If you receive an A4 document but only have Letter paper (or vice versa), set the printer to "Fit to Page" or "Scale to Paper" to avoid clipping. For critical layouts, always print on the correct size.
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Paper Sizes Chart
Frequently Asked Questions
Q: What is the difference between A4 and Letter?
A: A4 is 210 × 297 mm (8.27 × 11.69 in). Letter is 216 × 279 mm (8.5 × 11 in). Letter is slightly wider and shorter. They look nearly identical at a glance but differ enough to cause layout issues when mixed.
Q: What paper size should I use for a CV/résumé?
A: Use A4 if you are applying in Europe, Asia, or most of the world. Use Letter if applying in the US or Canada. Sending the wrong size can cause display issues when opened in different regions.
Q: How do I print A4 on a US printer?
A: Most US printers support A4. Load A4 paper and select "A4" in the print dialog under Paper Size. If the option is missing, check your printer driver settings or download updated drivers.