--- title: 'A3 Paper Size: 29.7 × 42 cm (11.69 × 16.54 in) | Two A4 Sheets, A3 vs Tabloid 11 × 17 and Pixels' url: https://joelin.cc/en/p/9609 source: https://joelin.cc/en/p/9609 lang: en pubDate: '2026-10-19' date_modified: '2026-10-19' description: 'A3 paper is 29.7 × 42 cm (297 × 420 mm), about 11.69 × 16.54 in: two A4 sheets side by side, 3508 × 4961 px at 300 DPI, and not the same as Tabloid 11 × 17.' author: joe ai_role: ai_only translation_of: /p/9609 mentions: - name: A4 sameAs: - https://www.wikidata.org/wiki/Q280184 - name: ISO 216 sameAs: - https://www.wikidata.org/wiki/Q839751 --- # A3 Paper Size: 29.7 × 42 cm (11.69 × 16.54 in) | Two A4 Sheets, A3 vs Tabloid 11 × 17 and Pixels A3 paper is 29.7 × 42 cm, or about 11.69 × 16.54 inches. People who look up the A3 size usually have something in hand that will not fit on A4: a poster, a large chart, a restaurant menu, or a design proof. Here are the answers first: ## A3 size quick reference | Unit | A3 size | | --- | --- | | Centimeters | 29.7 × 42 cm | | Millimeters | 297 × 420 mm | | Inches | about 11.69 × 16.54 in | One sentence is all you need to remember: A3 is two A4 sheets put together. A4 is 21 × 29.7 cm, so two side by side make 42 × 29.7 cm. Turn that sideways and you have A3's 29.7 × 42 cm. ![A3 is 29.7 × 42 cm, equal to two A4 sheets side by side. US Tabloid is 11 × 17 inches (27.94 × 43.18 cm), which is not the same as A3.](https://image.joelin.cc/cdn-cgi/imagedelivery/0xu8EsaSar9n3zUKY5d7xw/joelin/2026-08/a3-size-guide-v2/hero) ## Where A3 sits in the A series: the folding logic The whole A-series family follows one rule: each step is a fold in half (or a doubling), and the aspect ratio is fixed at 1 : √2, so the shape stays the same after folding. | Size | cm | Relationship to A3 | | --- | --- | --- | | A2 | 42 × 59.4 | Twice A3 (two A3 sheets side by side) | | A3 | 29.7 × 42 | Reference size | | A4 | 21 × 29.7 | A3 folded in half | | A5 | 14.8 × 21 | A3 folded in half twice | The same move works in both directions: A3 folded is A4, and A4 folded is A5; double A3 and you get A2. Designers often proof at A3 and deliver at A4 for exactly this reason. Because folding does not distort the shape, the layout scales proportionally without being rearranged. The complete folding family tree, including the smaller sizes from A6 down, is covered in [A6 Paper Size](/en/p/9020). A4 has its own guide, including the differences from Letter: [A4 Paper Size](/en/p/9607). The larger sizes each have a guide too: [A2 Size](/en/p/9612) (twice A3) and [A1 Size](/en/p/9611). ## What A3 is used for - Posters and event notices: A4 on a wall is too small to read from a distance, and A3 is the largest common size you can usually print yourself without a wide-format printer. - Charts and reports: organization charts, Gantt charts and financial statements spread out on one A3 page instead of two A4 pages. - Restaurant menus: an A3 sheet folded in half becomes a four-page menu at A4 size, a classic menu structure. - Design proofs: layout details printed at twice the size make typos and alignment problems impossible to miss. ## Where can you print A3? Many office multifunction printers and copy shops can handle large sheets, but check which paper the machine actually stocks. In North America, the large sheet you will usually find in office printers and copy shops is Tabloid (11 × 17 in) rather than A3, and the two are not interchangeable (see the last section). If a file was designed for A3, either ask for A3 paper or set the print dialog to scale the page to fit. The way you send the file can matter too: some upload or cloud-printing routes support fewer paper sizes than printing directly at the machine, so confirm before you go. Anything larger than A3 usually needs a wide-format printer at a print shop. ## How many pixels do you need to print A3? The conversion formula is: millimeters ÷ 25.4 × DPI. | Resolution | Pixels (297 × 420 mm) | Typical use | | --- | --- | --- | | 600 DPI | 7016 × 9921 px | Archival scans of text and line art, fine-art inkjet prints | | 300 DPI | 3508 × 4961 px | Files sent to print, posters viewed up close | | 150 DPI | 1754 × 2480 px | Displays viewed from a distance, internal documents | | 72 DPI | 842 × 1191 px | Screen previews only; not recommended for print | Use 300 DPI for anything people will look at up close, such as menus and proofs. For a poster on a wall that people will view from a distance, 150 DPI is usually enough. A3 covers a large area, and a 300 DPI file can easily run to tens of megabytes, so choosing the resolution by viewing distance can save a lot of upload time. ### How the A3 pixel numbers are calculated Every pixel figure for A3 comes from the same steps: divide millimeters by 25.4 to get inches, multiply by the DPI, then round to a whole pixel. At 300 DPI, the width is 297 ÷ 25.4 × 300 = 3507.9, which becomes 3508, and the height is 420 ÷ 25.4 × 300 = 4960.6, which becomes 4961. At 600 DPI the results are 7015.7 × 9921.3, rounded to 7016 × 9921. Because the A series is designed in metric units, its inch values always have decimals, so different software and websites sometimes disagree by one pixel. For example, 300 DPI is also often written as 3508 × 4960, depending on whether the decimal is truncated or rounded. A one-pixel difference has no visible effect on a print. ### Use 300 DPI for print; for screens, only the pixel count matters When you send a file to a printer or print shop, the standard is 300 DPI at actual size, which for A3 is 3508 × 4961 px. That is the baseline used across the printing industry. 600 DPI is only needed for scanning text and line art or for fine-art prints; ordinary posters and printed materials do not need it. If the file will only be viewed on a screen (in a presentation, on a web page or on a phone), the DPI number does not affect sharpness, because screens only care about the total pixel count. The traditional convention is the 72 DPI set, 842 × 1191 px. If people will zoom in to check details on a phone or high-resolution display, the 150 DPI set, 1754 × 2480 px, is more than enough. ## A3 vs Tabloid: the same "two standards" story again The US system has no A3. Its counterpart is Tabloid (also called Ledger), 11 × 17 inches, or 27.94 × 43.18 cm. Tabloid is almost 2 cm narrower than A3 and about 1 cm longer. | Size | cm | Inches | | --- | --- | --- | | A3 (ISO) | 29.7 × 42 | about 11.69 × 16.54 | | Tabloid / Ledger (US) | 27.94 × 43.18 | 11 × 17 | This is the same story as A4 vs Letter: most of the world uses the ISO A series, while the United States uses its own inch-based sizes. In practice the trap is templates. Poster and report templates downloaded from US websites are often set up for Tabloid, and printing them on A3 paper leaves white margins or cuts content off. The same happens in reverse when an A3 file is sent to a US print service. When a file crosses standards, check whether the page setup says 297 × 420 mm or 11 × 17 in before printing. That costs far less than a stack of misprinted paper. ## Frequently asked questions ### How many centimeters is A3? 29.7 × 42 cm, or 297 × 420 mm, which is about 11.69 × 16.54 inches. It is exactly two A4 sheets (21 × 29.7 cm) side by side. ### How much bigger is A3 than A4? A3 has twice the area of A4. A3 folded in half is A4. That is the A-series folding logic: each step is a fold or a doubling, and the aspect ratio is fixed at 1 : √2. ### How many pixels do you need to print A3? 3508 × 4961 px at 300 DPI for print, 1754 × 2480 px at 150 DPI, and 842 × 1191 px at 72 DPI. Use 300 DPI for posters viewed up close; 150 DPI is usually enough for displays viewed from a distance. ### Can I print A3 at a copy shop or on an office printer? Often, yes, but check which paper the machine stocks. In North America the large sheet is usually Tabloid (11 × 17 in) rather than A3, and some upload or cloud-printing routes support fewer sizes than printing at the machine, so confirm before you go. ### Is A3 the same as Tabloid (11 × 17)? No. Tabloid (also called Ledger) is the US 11 × 17 inch size, or 27.94 × 43.18 cm, slightly narrower and slightly longer than A3. Printing a US template directly on A3 leaves white margins or cuts content off, the same trap as A4 vs Letter. ### How many pixels is A3 at 600 DPI? 7016 × 9921 px. The calculation is 297 ÷ 25.4 × 600 = 7015.7 and 420 ÷ 25.4 × 600 = 9921.3, rounded to whole numbers. For ordinary printing, 300 DPI (3508 × 4961 px) is enough; 600 DPI is mostly used for scanning text and line art or for fine-art output. Keywords: A3 paper size, A3 size in cm, A3 size in inches, A3 dimensions, A3 vs Tabloid, A3 poster, A3 in pixels Sources: The original Chinese article was first published on August 18, 2026, and last updated on September 30, 2026. A-series dimensions are fixed by the ISO 216 international standard; Tabloid (Ledger) is a North American inch-based size. The Chinese original's section on printing A3 at Taiwanese convenience stores has been replaced with general advice.