A3 Millimetres to Inches Converter
Instantly convert A3 paper dimensions from millimetres to inches. Accurate, free, and perfectly formatted for designers, printers, and students.
Calculate Your Paper Dimensions
Enter your dimensions in millimetres below to get an instant, precise conversion to inches. Pre-loaded with standard A3 dimensions for your convenience.
Dimension Converter
Input millimetres to see the exact inch equivalent
Standard A3 width is 297 mm
Standard A3 height is 420 mm
Converted Dimensions
Exact inch equivalents based on 1 inch = 25.4 mm
Standard ISO Paper Sizes
Common international paper dimensions in both millimetres and inches for quick comparison.
| Paper Size | Millimetres (mm) | Inches (in) |
|---|---|---|
| A2 | 420 × 594 mm | 16.54 × 23.39 in |
| A3 | 297 × 420 mm | 11.69 × 16.54 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 |
Paper Size FAQ
Everything you need to know about A3 dimensions, conversions, and international paper standards.
The standard ISO 216 A3 paper size is exactly 297 mm × 420 mm. When converted to inches, this equals approximately 11.69 inches × 16.54 inches.
To convert millimetres to inches, divide the millimetre value by 25.4, since there are exactly 25.4 millimetres in one inch. For example, 297 mm ÷ 25.4 = 11.69 inches.
All ISO A-series paper sizes, including A3, share the same aspect ratio of 1:√2 (approximately 1:1.414). This ensures that when you fold an A3 sheet in half, it becomes an A4 sheet with the exact same proportions, making scaling documents seamless.
Yes, A3 is exactly twice the size of A4. While A4 measures 210 mm × 297 mm (8.27 × 11.69 inches), A3 measures 297 mm × 420 mm (11.69 × 16.54 inches). A3 is commonly used for posters, diagrams, and large-format printing.