ISO 216 · A-series
A4 paper size — 210 × 297 mm
A4 is 210 × 297 millimetres — approximately 8.27 × 11.69 inches, and 2480 × 3508 pixels at 300 DPI (794 × 1123 px at 96 DPI for screens). It is the world's default document size: office paper, school work, contracts and printer trays across every continent except North America.
A4 — instant conversion
| Unit | Width | Height |
|---|---|---|
| Millimetres (mm) | 210 mm | 297 mm |
| Centimetres (cm) | 21 cm | 29.7 cm |
| Inches (in) | 8.268 in | 11.693 in |
| Pixels @ 300 DPI | 2480 px | 3508 px |
| PostScript points (pt) | 595.3 pt | 841.9 pt |
| Picas | 49.61 | 70.16 |
Change the DPI selector to see the pixel resolution at 72, 96, 150, 200, 300 or 600 DPI. Physical dimensions (mm, cm, in, pt, picas) do not change with DPI.
A4 in pixels at every DPI
The most common question about A4 is its pixel size — and the answer depends entirely on the DPI (dots per inch) you render at. Physical dimensions never change; the pixel count scales linearly with DPI.
| DPI | Width (px) | Height (px) | Typical use |
|---|---|---|---|
| 72 | 595 | 842 | Legacy screen standard |
| 96 | 794 | 1123 | Windows / web display |
| 150 | 1240 | 1754 | Draft print, large posters |
| 200 | 1654 | 2339 | Everyday office scans |
| 300 | 2480 | 3508 | Commercial print standard |
| 600 | 4961 | 7016 | Fine text, archival scans |
Other units: A4 is 8.268 × 11.693 in, 595.3 × 841.9 pt (PostScript points, the values PDF libraries use), and 49.61 × 70.16 picas.
A4 · 210 × 297 mm
A4 vs US Letter and neighbours
| Size | Millimetres | Inches | vs A4 | Compare |
|---|---|---|---|---|
| A3 | 297 × 420 | 11.69 × 16.54 | 2 × A4 | A3 page |
| A4 | 210 × 297 | 8.27 × 11.69 | — | (this page) |
| A5 | 148 × 210 | 5.83 × 8.27 | ½ × A4 | A4 vs A5 |
| US Letter | 215.9 × 279.4 | 8.5 × 11 | +6 mm W, −18 mm H | A4 vs Letter |
| US Legal | 215.9 × 355.6 | 8.5 × 14 | taller, wider | Legal |
The A4 / Letter difference matters in practice: printing an A4 document on Letter without scaling shrinks the bottom margin, and vice versa the right margin. If a layout must look identical on both, keep all critical content at least 15 mm from every edge.
Where A4 is used
- Office documents, contracts and reports worldwide (except North America)
- School and university work, theses and exams
- Government forms and official correspondence
- CVs and cover letters for international applications
- Printer-friendly PDFs and ebook exports
- Letterheads, invoices and business stationery
Design specs for A4 print
- Bleed
- 3 mm each side → export at 216 × 303 mm
- Safe area
- keep text inside 204 × 291 mm (3 mm inset)
- Office margins
- 25.4 mm (1 in) standard · 15 mm tight
- Print-ready image
- 2480 × 3508 px minimum at 300 DPI
- File format
- PDF/X-1a for offset · plain PDF fine for digital press
The maths behind A4
The A-series starts from A0, derived from an area of one square metre (rounded to 841 × 1189 mm) with a 1 : √2 (≈ 1 : 1.414) aspect ratio. Halving A0 along the long edge gives A1, halving again gives A2, then A3, then A4. Because √2 is the only ratio that survives halving unchanged, every size in the series has identical proportions — which is why an A4 design scales to A5 or A3 with zero distortion and no cropping.
A4 is the fourth halving: 1 m² ÷ 16 ≈ 0.0625 m², or exactly 623.7 cm². Sixteen A4 sheets nominally tile one A0 — edge to edge they cover 840 × 1188 mm of its 841 × 1189 mm; the missing millimetre per axis is the footprint of whole-millimetre rounding.
Frequently asked questions
What is A4 size in pixels?
It depends on the DPI. At 300 DPI (print standard) A4 is 2480 × 3508 pixels. At 150 DPI it is 1240 × 1754 px. At 96 DPI (typical screen) it is 794 × 1123 px, and at 72 DPI it is 595 × 842 px.
What are the exact dimensions of A4?
A4 is exactly 210 × 297 millimetres, defined by ISO 216. That is 21.0 × 29.7 cm, or approximately 8.27 × 11.69 inches.
What A4 pixel size should I use for a document scan or design?
For anything you intend to print, work at 300 DPI: 2480 × 3508 pixels. For screen-only documents 150 DPI (1240 × 1754 px) is a reasonable balance of sharpness and file size. Avoid 72 DPI for anything that might ever be printed.
Is A4 the same as US Letter?
No. A4 is 210 × 297 mm; US Letter is 215.9 × 279.4 mm (8.5 × 11 in). Letter is about 6 mm wider and 18 mm shorter. Documents designed for one usually print on the other, but margins shift and edge-aligned elements move.
Why does A4 have a 1 : √2 aspect ratio?
ISO 216 defines the ratio so that folding a sheet in half along the long edge produces the next size down with identical proportions. A4 folded gives A5; two A4 sheets side by side give A3. Scaling between sizes never distorts the layout.
What margins should I use for an A4 document?
Office documents typically use 25.4 mm (1 inch) on all sides. Tight layouts can go to 15 mm. Academic theses and long-form reading often use 30–35 mm. Home printers cannot print inside roughly the outer 3–5 mm regardless of margin setting.
What is A4 with bleed?
For full-bleed commercial printing, add 3 mm on every side: the export size becomes 216 × 303 mm with the trim line at 210 × 297 mm. Keep critical text at least 3–5 mm inside the trim.
How many A4 pages is one A3, A2, A1 or A0 sheet?
A3 = 2 × A4 exactly (two A4 side by side are 420 × 297 mm — a perfect A3). Higher steps are nominal: A2 = 4 × A4 exactly as well, while A1 ≈ 8 × A4 and A0 ≈ 16 × A4, each a millimetre shy because ISO rounds sizes to whole millimetres. A0 is derived from an area of one square metre (999,949 mm² at the rounded dimensions).
What file size is a 300 DPI A4 scan?
A 300 DPI A4 page is about 8.7 megapixels (2480 × 3508). As an uncompressed 24-bit image that is ~26 MB; as a JPEG typically 1–4 MB depending on content and quality; as a searchable PDF usually 100–500 KB per page.
What is A4 in points for PDF and CSS?
A4 is 595.3 × 841.9 PostScript points. This is why PDF libraries and CSS @page rules commonly reference 595 × 842 pt as the A4 page box.