Paper Size Reference
Look up paper dimensions for A0-A6, US Letter, Legal, Tabloid, and B-series in inches, mm, and cm.
Includes area and aspect ratio for each standard.
Paper sizes follow two main international standards: the ISO 216 series (used in most of the world) and the ANSI/ASME series (used primarily in the United States and Canada). Understanding how they relate helps when printing, scanning, or designing documents for international distribution.
ISO 216 formula (the elegant math behind A-sizes): Each A-size is exactly half the next larger size. The ratio of long side to short side is always √2 ≈ 1.41421: Width × √2 = Length A(n) dimensions = A(n−1) dimensions ÷ √2
This means A4 folded in half becomes A5. A3 folded in half becomes A4. The area halves each step, but the proportions stay identical — brilliant for printing and scaling.
Common sizes:
| Size | mm | inches |
|---|---|---|
| A3 | 297 × 420 | 11.69 × 16.54 |
| A4 | 210 × 297 | 8.27 × 11.69 |
| A5 | 148 × 210 | 5.83 × 8.27 |
| A6 | 105 × 148 | 4.13 × 5.83 |
| US Letter | 216 × 279 | 8.5 × 11 |
| US Legal | 216 × 356 | 8.5 × 14 |
| US Tabloid | 279 × 432 | 11 × 17 |
Key differences: A4 vs. US Letter:
- A4 is taller and narrower; US Letter is shorter and wider.
- A4: 8.27 × 11.69 inches. Letter: 8.5 × 11 inches.
- Printing a US Letter document on A4: content may be cut off at the bottom unless scaled.
- Printing an A4 document on US Letter: small white bands appear on sides.
Worked example (scaling): You have an A4 layout (210 × 297 mm) and need to print on US Letter (216 × 279 mm). Scale to fit: width scale = 216 ÷ 210 = 102.9%; height scale = 279 ÷ 297 = 93.9%. The limiting factor is height — scale to 93.9% to fit without clipping.
Tip: Always design in A4 if your audience is international — it is the global default for business documents, academic papers, and legal correspondence outside North America.