Paper Size Converter

Compare A-series, B-series, Letter, Legal, and Tabloid paper sizes in mm, cm, and inches.

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Paper Size Reference Table

SizeCategoryDimensions (mm)Dimensions (inches)Area (cm²)
A0ISO A841 × 1189 mm33.1 × 46.8 in9999.5 cm²
A1ISO A594 × 841 mm23.4 × 33.1 in4995.5 cm²
A2ISO A420 × 594 mm16.5 × 23.4 in2494.8 cm²
A3ISO A297 × 420 mm11.7 × 16.5 in1247.4 cm²
A4ISO A210 × 297 mm8.3 × 11.7 in623.7 cm²
A5ISO A148 × 210 mm5.8 × 8.3 in310.8 cm²
A6ISO A105 × 148 mm4.1 × 5.8 in155.4 cm²
LetterUS216 × 279 mm8.5 × 11.0 in602.6 cm²
LegalUS216 × 356 mm8.5 × 14.0 in769.0 cm²
TabloidUS279 × 432 mm11.0 × 17.0 in1205.3 cm²

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Compare Two Sizes

Letter
A4

Visual comparison (not to exact scale)

A4 is
103.5%
the area of Letter
(+3.5% difference)
A4 Area
623.7 cm²
Letter Area
602.6 cm²
Dimensions
A4210 × 297 mm
Letter216 × 279 mm

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Understanding Paper Size Standards

Paper sizes around the world follow two main standards: ISO 216 (used in most of the world) and North American sizes (used in the US, Canada, and parts of Mexico).

ISO 216 — The A-Series

The ISO 216 standard defines the A, B, and C series of paper sizes. The A-series is the most common. It is based on a single aspect ratio of √2 ≈ 1.414 (1:√2). This unique ratio means that when you fold a sheet in half along its longest side, the resulting page has the exact same proportions as the original.

  • A0 has an area of exactly 1 square meter (841 × 1189 mm).
  • Each subsequent size (A1, A2, A3…) is half the area of the previous one.
  • A4 (210 × 297 mm) is the standard for letters, documents, and printing worldwide.

North American Paper Sizes

The United States, Canada, and a few other countries use a different set of paper sizes defined by the American National Standards Institute (ANSI). These sizes do not share a consistent aspect ratio.

  • Letter (8.5 × 11 in / 216 × 279 mm) is the standard for everyday documents and business correspondence.
  • Legal (8.5 × 14 in / 216 × 356 mm) is commonly used for contracts and legal documents.
  • Tabloid (11 × 17 in / 279 × 432 mm) is popular for newspapers, brochures, and large-format printing.

Why Do A4 and Letter Cause Printing Issues?

Because A4 and Letter have different dimensions and aspect ratios, a document formatted for one may not fit correctly on the other. A4 is slightly narrower and taller than Letter. When printing A4 documents on Letter paper, content near the bottom may be cut off, while Letter documents on A4 may have extra margins on the sides.

Quick Tip

When designing documents for international audiences, use A4 as the default. Most modern software and printers can scale documents between A4 and Letter, but always check the print preview before sending to the printer.

Frequently Asked Questions

A4 paper measures 210 × 297 millimeters (8.3 × 11.7 inches). It is the standard paper size for documents in most countries outside North America.

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