A4 paper measures 210 mm by 297 mm.
This standard size, defined by ISO 216, is widely used globally for documents and printing.

Core Dimensions

A4's exact size is 210 x 297 millimeters (or 21 x 29.7 centimeters), giving it an aspect ratio of 1:√2 for efficient scaling across the A series.

In inches, that's 8.27 x 11.69 , slightly taller and narrower than US Letter (8.5 x 11).

Its surface area is about 0.063 square meters (0.68 square feet), making it practical for everyday use like letters and reports.

Comparison Table

Size| mm (Width x Height)| Inches| Common Use
---|---|---|---
A3| 297 x 420| 11.7 x 16.5| Posters, spreadsheets 35
A4| 210 x 297| 8.3 x 11.7| Documents, books 19
A5| 148 x 210| 5.8 x 8.3| Notebooks, flyers 5
US Letter| 216 x 279| 8.5 x 11| North American standard 1

Everyday Context

Imagine folding an A3 sheet in half lengthwise—you get A4, a clever design from 1920s German engineering for scalability.

In February 2026 offices worldwide, A4 remains the go-to for printing, from resumes to menus, though digital shifts reduce physical use.

Printers often default to it in Europe, Asia, and beyond, unlike Letter- dominant US setups.

Quick Facts

  • Pixels at 300 DPI : 2480 x 3508 (ideal for high-res prints).
  • Half A3, double A5 : Perfect for nesting in binders or envelopes.
  • Global standard : Adopted in 178 countries, but not North America.

TL;DR : A4 is 210x297mm—compact, versatile, and the world's printing workhorse.

Information gathered from public forums or data available on the internet and portrayed here.