概要
A3 paper measures 297 × 420 mm, or about 11.69 × 16.54 inches. It is exactly twice the area of A4, which makes it useful for posters, wall charts, diagrams, and proof sheets that need more room than a standard office page.
A3 is close to US 11×17 Tabloid, but it is not interchangeable. Use the exact page size in your PDF and print at 100 percent scale so metric grids, margins, and labels do not drift.
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関連ガイド記事
Printing on A3 Paper: When to Use It and Avoid Scaling
Use this guide to choose A3 for posters, charts, and proofs, compare it with A4 and 11x17, and avoid cropping or accidental scaling.
A3 vs A4 Paper Size: Dimensions, Uses and Print Scaling
Compare A3 at 297 x 420 mm with A4 at 210 x 297 mm. Choose the right sheet for documents or diagrams and avoid print scaling errors.
Paper Sizes: ISO vs ANSI, Letter, Legal, A4, and 11x17
Compare ISO and North American paper sizes: A4, A3, Letter, Legal, Tabloid, Ledger, and 11x17. Choose the right size before exporting PDFs.
よくある質問
What is A3 paper size in inches?
A3 paper is about 11.69 × 16.54 inches.
What is A3 paper size in millimeters?
A3 paper is 297 × 420 mm.
Is A3 the same as 11x17?
No. A3 is 297 × 420 mm, while 11x17 Tabloid is 279.4 × 431.8 mm. They are close enough to confuse, but not interchangeable for scale-sensitive printables.