Paper Size Converter
Pick a paper size — A4, Letter, A3, Legal and every ISO and US standard — or enter a custom size, then see it in pixels, mm, cm, inches and points at any DPI. Copy any value with one tap.
Quick pick
Dimensions of A4
Pixel size depends on the DPI you choose. Use 300 DPI for print, 96 DPI for screen reference and 72 DPI for legacy/PostScript. mm, cm, inches and points are fixed and do not change with DPI.
Common paper sizes compared
| Paper size | Millimetres (mm) | Inches (in) | px @300 |
|---|---|---|---|
| A3 | 297 × 420 | 11.69 × 16.54 | 3508 × 4961 |
| A4 | 210 × 297 | 8.27 × 11.69 | 2480 × 3508 |
| A5 | 148 × 210 | 5.83 × 8.27 | 1748 × 2480 |
| A6 | 105 × 148 | 4.13 × 5.83 | 1240 × 1748 |
| Letter | 215.9 × 279.4 | 8.5 × 11 | 2550 × 3300 |
| Legal | 215.9 × 355.6 | 8.5 × 14 | 2550 × 4200 |
| B5 | 176 × 250 | 6.93 × 9.84 | 2079 × 2953 |
Pixel dimensions shown at 300 DPI (standard print quality). At 96 DPI multiply nothing — divide these by ~3.125; at 72 DPI multiply the inches by 72.
About paper sizes
Most of the world uses the ISO 216 standard, which defines the familiar A series (A0 down to A10), the B series and the C series for envelopes. Its clever property is the √2 aspect ratio: every sheet is exactly 1 : √2 (about 1 : 1.414), so cutting a sheet in half across its longer side gives the next-smaller size with the same proportions and no wasted paper. A0 has an area of exactly one square metre, and each step down (A0 → A1 → A2 …) halves the area. A4, at 210×297 mm, is the most common everyday size — the default for documents, printers and PDFs almost everywhere. The big exception is North America, which uses Letter (8.5×11 in), Legal (8.5×14 in) and Tabloid/Ledger (11×17 in) instead. Pixel dimensions are not a fixed property of a sheet: they depend on the DPI (dots per inch) you render at. Print work uses 300 DPI, on-screen design uses 96 DPI, and 72 DPI is the legacy PostScript value. This tool covers every ISO and US size in mm, cm, inches, points and pixels at any DPI.
How to use the paper size converter
- 1 Pick a paper size from the quick chips or the grouped dropdown (A4, Letter, A3…), or choose "Custom size" and type a width and height in millimetres.
- 2 Choose the orientation (portrait or landscape) and the resolution — 300 DPI for print, 96 DPI for screen, or type any custom DPI.
- 3 Read the dimensions in pixels, mm, cm, inches and points, and tap the copy button on any card to copy a value ready to paste.
The math
Every size is stored in millimetres and converted with exact ratios: cm = mm ÷ 10. in = mm ÷ 25.4 (1 inch is defined as exactly 25.4 mm). pt = mm ÷ 25.4 × 72, because 1 point = 1/72 inch. px = mm ÷ 25.4 × DPI, rounded to a whole pixel. Landscape simply swaps width and height. For ISO 216 sizes the long side is the short side × √2, which is why A4 (210×297 mm) folds down to A5, A6 and so on with identical proportions. So A4 at 300 DPI is 210 ÷ 25.4 × 300 ≈ 2480 px wide and 297 ÷ 25.4 × 300 ≈ 3508 px tall.
Frequently asked questions
What is A4 in pixels?
A4 is 210×297 mm, and its pixel size depends on the DPI. At 300 DPI (standard print) A4 is 2480×3508 px. At 96 DPI (screen reference) it is 794×1123 px, and at 72 DPI it is 595×842 px. The formula is px = mm ÷ 25.4 × DPI, so 210 ÷ 25.4 × 300 ≈ 2480 px wide and 297 ÷ 25.4 × 300 ≈ 3508 px tall.
What is A4 in inches and millimetres?
A4 is 210×297 mm, which is 21.0×29.7 cm or 8.27×11.69 inches (210 ÷ 25.4 = 8.27 in, 297 ÷ 25.4 = 11.69 in). In points it is 595.3×841.9 pt. A4 is the most common document size outside North America.
What is the difference between Letter and A4?
US Letter is 8.5×11 inches (215.9×279.4 mm); A4 is 210×297 mm (8.27×11.69 in). Letter is slightly wider (by about 6 mm / 0.23 in) and slightly shorter (by about 18 mm / 0.7 in) than A4. Letter is the standard in the United States, Canada and a few other countries, while A4 is the ISO 216 standard used by the rest of the world. They are not interchangeable, so check which one a printer or form expects.
What DPI should I use for printing?
Use 300 DPI for standard print quality — it is the value most print shops and photo labs expect, and it is high enough that individual dots are invisible at normal reading distance. Use 600 DPI for fine line art or professional work, and 150 DPI for quick drafts. For anything that will only be viewed on screen, 96 DPI (the CSS reference) is enough. Higher DPI means more pixels and larger files, so match the DPI to how the document will be used.
Related tools
Need to make the paper yourself? Use the printable paper templates generator for grid, lined and dot paper. For web work, the CSS unit converter turns px into rem, em, pt, % and viewport units, and the aspect ratio calculator helps you size images and layouts.