Paper Size Converter

Q: A4 vs Letter — what’s the difference?

A4 measures 210 × 297 mm (8.27 × 11.69 in), while US Letter is 216 × 279 mm (8.5 × 11 in). A4 is taller and slightly narrower.

Q: What’s the A-series aspect ratio?

All ISO A-series sizes keep a 1:√2 ratio (≈ 1.414). Each size is half the area of the previous one when cut parallel to its shorter side.

Select a paper size and see its dimensions in millimeters and inches, with aspect ratio and a visual preview.

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FAQ

A4 vs Letter — what’s the difference?

A4 is 210 × 297 mm (8.27 × 11.69 in), while US Letter is 216 × 279 mm (8.5 × 11 in). A4 is taller and slightly narrower.

What’s the A-series aspect ratio?

All ISO A-series sizes keep a 1:√2 ratio (≈ 1:1.414). Each size is half the area of the previous one when cut parallel to its shorter side.

Paper Sizes Converter — A4, Letter, Legal & More

Easily convert between paper sizes such as A4, A3, Letter, and Legal with this quick tool. It’s perfect for designers, print professionals, and office work, letting you understand size differences across regions. Compare international ISO paper standards (A-series) with North American formats.

For example, A4 measures 210 × 297 mm, while Letter size is 216 × 279 mm. This converter helps you adjust margins, layouts, and print settings without confusion.

You may also like our area converter to calculate surface measurements in metric or imperial units.

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Paper Sizes Converter — A4, Letter, Legal & More