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Paper Size ConverterCompare paper sizes: A0-A10, B0-B10, Letter, Legal, and Tabloid with dimensions in mm and inches.

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Paper Size Converter

Compare paper sizes: A0-A10, B0-B10, Letter, Legal, and Tabloid with dimensions in mm and inches.

How to Use
1

Select two papers

Choose two paper sizes to compare side by side.

2

View dimensions

See dimensions in both millimeters and inches.

3

Browse all sizes

Filter and browse the complete paper size reference table.

What Is Paper Size Converter?

A paper size converter lets you compare and look up the dimensions of international standard paper sizes. The ISO 216 standard defines the A series (A0-A10) and B series (B0-B10), where each successive size is half the previous one while maintaining the same aspect ratio (1:√2). North American standard sizes (Letter, Legal, Tabloid) follow a different system. A4 (210 × 297 mm) is the global standard for documents, while US Letter (8.5 × 11 inches) is standard in the United States and Canada. This tool provides dimensions in both millimeters and inches with a visual comparison feature.

Why Use Our Paper Size Converter?

  • Complete A and B series plus US sizes with exact dimensions.
  • Dimensions in both mm and inches.
  • Visual side-by-side comparison of any two paper sizes.
  • Filterable by series (A, B, US).
  • Essential reference for printing and design.

Common Use Cases

Print Design

Set up correct page dimensions for international printing projects.

Document Formatting

Understand size differences when sharing documents internationally (A4 vs Letter).

Poster & Signage

Choose the right paper size for large-format printing.

Envelope Selection

Match paper sizes to appropriate envelope sizes.

Technical Guide

ISO 216 paper sizes: The A series starts with A0 (841 × 1189 mm), which has an area of exactly 1 m². Each subsequent size (A1, A2, ...) is created by folding the previous size in half along the long edge. The aspect ratio 1:√2 (≈ 1:1.414) is maintained throughout, meaning content can be scaled between sizes without distortion. The B series provides intermediate sizes between A sizes. B0 (1000 × 1414 mm) has a geometric mean between A0 and A1. US sizes are independent of ISO standards: • Letter: 8.5 × 11 in (215.9 × 279.4 mm) • Legal: 8.5 × 14 in (215.9 × 355.6 mm) • Tabloid: 11 × 17 in (279.4 × 431.8 mm) A4 is slightly narrower and taller than Letter. This difference can cause formatting issues when sharing documents between countries.

Tips & Best Practices

  • 1
    A4 is used worldwide except in the US/Canada, which use Letter size.
  • 2
    A4 is 210 × 297 mm; Letter is 215.9 × 279.4 mm — close but not interchangeable.
  • 3
    Each A size is exactly half the previous one: A3 = 2×A4, A4 = 2×A5.
  • 4
    For printing at home, ensure your document's page size matches your paper.

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Frequently Asked Questions

QWhat is the difference between A4 and Letter size?
A4 is 210 × 297 mm (8.27 × 11.69 in). Letter is 215.9 × 279.4 mm (8.5 × 11 in). Letter is slightly wider and shorter.
QHow big is A3?
A3 is 297 × 420 mm (11.69 × 16.54 in) — exactly twice the area of A4.
QWhat is the aspect ratio of A-series paper?
1:√2 (approximately 1:1.414). This unique ratio means folding in half always produces the next smaller size with the same proportions.
QWhat is A0 size?
A0 is 841 × 1189 mm, with an area of exactly 1 square meter. All other A sizes derive from it by successive halving.
QIs Legal size the same as A4?
No. Legal (8.5 × 14 in = 215.9 × 355.6 mm) is the same width as Letter but much taller than A4.

About Paper Size Converter

Paper Size Converter is a free online tool from FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration required. No ads. Just fast, reliable tools.