Unit Converters

Paper Size Converter

Convert between ISO A/B paper sizes, North American sizes, photo sizes, and envelopes instantly.

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What is Paper Size Converter?

A paper size converter is a free online tool that helps you convert between different international paper size standards. Whether you're working with ISO A/B series, North American sizes, photo dimensions, or envelope standards, this tool instantly shows the closest equivalent size.

Steps:

  1. Select the source paper size series
  2. Select the target paper size series
  3. Choose the specific paper size from the dropdown
  4. View the closest equivalent size with dimensions

Use Cases

  • Printing documents from international sources
  • Selecting the right paper for your printer
  • Converting between A4 and Letter for international projects
  • Finding photo print sizes and envelope standards

Key Benefits

  • Instant conversion between 5 paper size series
  • Includes dimensions in mm and inches
  • Covers ISO A/B, North American, photo, and envelope sizes
  • Shows closest equivalent size

Pro Tips

  • A4 is the standard in most countries outside North America
  • Always check your printer's supported paper sizes
  • The 1:√2 aspect ratio means scaling between A sizes preserves proportions
  • Photo sizes and envelope sizes vary by region

Key Terms Explained

ISO 216: International standard for paper sizes defining A, B, and C series
Aspect Ratio: The ratio of width to height — 1:√2 for ISO paper sizes
A4: The most common paper size worldwide (210 × 297 mm)
Letter: The standard paper size in North America (8.5 × 11 inches)

Related Concepts

Frequently Asked Questions

What is ISO A4 paper size?
A4 is the most commonly used paper size worldwide. It measures 210 × 297 mm (8.27 × 11.69 inches) and has an aspect ratio of 1:√2 (approximately 1:1.414).
What is the difference between A4 and Letter size?
A4 (210 × 297 mm) is slightly narrower and taller than US Letter (216 × 279 mm / 8.5 × 11 inches). A4 is used in most countries, while Letter is standard in North America.
How are ISO paper sizes calculated?
ISO paper sizes follow a mathematical system where each size has an aspect ratio of 1:√2. Folding a sheet in half produces the next smaller size (e.g., A3 folded becomes A4).
What is the largest standard paper size?
ISO A0 is the largest standard A-series size at 841 × 1189 mm (33.1 × 46.8 inches). It has an area of exactly 1 square meter.
What is B-series paper used for?
ISO B-series sizes are between A-series sizes. B4 is between A3 and A4, B5 is between A4 and A5. B-sizes are commonly used for books, posters, and envelopes.
Why are North American paper sizes different?
North American paper sizes evolved from historical manufacturing standards and predate the ISO system. They don't follow the 1:√2 ratio and have different naming conventions.

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