Standards & Specs📅 2026-09-10⏱️ 5 min readBy Online Ruler Standards Team

A4, Letter & Paper Sizes: Dimensions in Inches, CM and MM Explained

Complete guide to international paper sizes: A4, US Letter, Legal, A3, and A5 dimensions in millimeters, centimeters, and inches with printable scale comparison.

Standard A4 paper measures 210 × 297 mm (21.0 × 29.7 cm or 8.27 × 11.69 inches). US Letter paper measures 8.5 × 11.0 inches (215.9 × 279.4 mm). A4 is taller and narrower, whereas US Letter is shorter and wider.

A4, Letter & Paper Sizes: Dimensions in Inches, CM and MM Explained
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Whether you are printing documents, creating digital artwork, configuring printer margins, or looking for an emergency measuring baseline, understanding standard paper dimensions is crucial.

A4 vs. US Letter: Key Differences

While both serve as the default standard for office documents, they are not interchangeable:

  • A4 Paper: 210 × 297 mm (8.27 × 11.69 inches). 6 mm narrower and 18 mm taller than Letter.
  • US Letter: 215.9 × 279.4 mm (8.5 × 11.0 inches). Wider but shorter than A4.

ISO 216 A-Series Paper Sizes Chart (A0 to A8)

Size Millimeters (mm) Centimeters (cm) Inches
A0841 × 1189 mm84.1 × 118.9 cm33.11 × 46.81″
A1594 × 841 mm59.4 × 84.1 cm23.39 × 33.11″
A2420 × 594 mm42.0 × 59.4 cm16.54 × 23.39″
A3297 × 420 mm29.7 × 42.0 cm11.69 × 16.54″
A4210 × 297 mm21.0 × 29.7 cm8.27 × 11.69″
A5148 × 210 mm14.8 × 21.0 cm5.83 × 8.27″

Frequently Asked Questions

Which countries use US Letter instead of A4?▼

The United States, Canada, and parts of Mexico and the Philippines primarily use US Letter. Almost every other country on earth uses the international ISO 216 standard (A4).

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