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Find exact standard dimensions for A0 to A13 paper sizes, featuring millimeter and inch conversions alongside visual proportion charts.
Do you ever struggle to remember the exact dimensions of A4 or A3 paper when designing, printing, or binding? This tool provides precise size data for the A series paper defined by the ISO 216 standard. The A series is the most widely used international paper size standard. Its core principle is that each time the paper is folded in half parallel to its shortest sides, the area is halved, but the aspect ratio (approximately 1:√2) remains constant. This tool allows you to look up 14 standard sizes from A0 (the largest) to A13 (the smallest), instantly outputting the width and height of each size in both millimeters (mm) and inches to help you quickly convert and compare dimensions.
Q: What are the exact dimensions of A4 paper?
A: The standard size of A4 paper is 210 mm × 297 mm (or 8.27 inches × 11.69 inches).
Q: How does the "folding" rule of A series paper sizes work? Why is A4 half the size of A3?
A: The A series follows the ISO 216 standard, which dictates that folding a paper size in half parallel to its shortest sides produces the next smaller size. For example, when A3 paper (297 mm × 420 mm) is folded in half along its longest side (420 mm), it yields two sheets of A4 paper (210 mm × 297 mm). Therefore, the area of A4 is exactly half that of A3, and all A series papers maintain the same aspect ratio (approximately 1:1.414).
This tool provides theoretical dimensions under the ISO 216 standard. During actual printing or cutting, finished sizes may vary slightly due to bleed, trimming margins, or specific implementation standards in different countries/regions. This is a static lookup tool; no personal information is required, and all calculations are performed locally on your device. Please use it with confidence.
For graphic designers and printing professionals, understanding A series sizes is fundamental. A practical tip is to memorize the A4 size (210 × 297 mm) as your baseline. A3 is twice the size of A4 (297 × 420 mm), and A5 is half the size of A4 (148 × 210 mm). In cross-media design, if you need to scale an A4 document up to an A3 poster, you theoretically only need to scale the original design proportionally to 141% (since the area doubles, the side lengths increase by a factor of √2 ≈ 1.414). Common application examples: standard business letters and documents typically use A4; brochures and booklets often use A5; while posters and engineering drawings generally use A3 or larger sizes like A2 and A1.
