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Paper Size Converter

Everyday

Compare paper sizes — A0 to A8, Letter, Legal, Tabloid, and more — in millimetres, centimetres, and inches. Find the right paper size instantly.

Millimetres (mm)
210 × 297 mm
Centimetres (cm)
21.0 × 29.7 cm
Inches (in)
8.27 × 11.69 in

All Paper Sizes

What is a Paper Size?

A Paper Size Converter shows the exact dimensions of standard paper sizes — the ISO 216 A-series used throughout most of the world, and the US sizes (Letter, Legal, Tabloid, Executive) used in North America — in millimetres, centimetres, and inches. Paper sizing is one of those details that rarely matters until it does: a document designed for A4 can print awkwardly on a Letter-size printer, and print shops, designers, and developers regularly need to know exact dimensions when setting up a layout.

This converter lets you pick any standard size and instantly see its dimensions across all three common units, alongside a full reference table for comparing every size at a glance. It pairs well with the Length Converter for general unit conversion and the Typography Unit Converter for print and design measurements.

How to use this Paper Size calculator

  1. Select a paper size from the Paper Size dropdown — choose from A0–A8 or the standard US sizes.
  2. Read the dimensions shown in Millimetres, the primary result.
  3. Check the Centimetres and Inches cards for the same dimensions in other units.
  4. Scroll the All Paper Sizes reference table to compare your selected size against every other standard size.
  5. Click any size in the reference table to instantly switch the main result to that size.

Formula & Methodology

Each paper size in this converter is defined by fixed, standardised width and height values rather than a single conversion formula — ISO 216 sizes are defined directly in millimetres, and US sizes are defined directly in inches, then converted using:

Millimetres = Inches × 25.4

The ISO 216 A-series additionally follows a fixed aspect ratio of 1:√2, meaning each size is exactly half the area of the size above it:

A(n+1) width = A(n) height ÷ 2, A(n+1) height = A(n) width

Worked example: A4 (210 × 297 mm) converts to inches as:
- Width: 210 ÷ 25.4 ≈ 8.27 in
- Height: 297 ÷ 25.4 ≈ 11.69 in

Frequently Asked Questions

A4 measures 210 × 297 mm (8.27 × 11.69 inches), while US Letter measures 215.9 × 279.4 mm (8.5 × 11 inches) — A4 is slightly narrower and noticeably taller than Letter. This difference is why documents formatted for A4 sometimes don't print cleanly on Letter-size printers, and vice versa.
A4 paper measures 8.27 × 11.69 inches (210 × 297 mm). It's the standard paper size used for documents, letters, and printing throughout most of the world outside North America.
Like all ISO 216 sizes, A4 is defined by a fixed aspect ratio of 1:√2 (roughly 1:1.414), so portrait A4 is 210 mm wide and 297 mm tall, while landscape A4 simply rotates those same dimensions. This ratio is what lets two A4 sheets combine to form one A3 sheet with no wasted space.
Each size in the A-series is exactly half the area of the size above it, achieved by folding or cutting along the longer dimension — two A4 sheets make one A3 sheet, two A3 sheets make one A2 sheet, and so on up to A0. This is why architects and engineers can scale drawings cleanly between A-series sizes without distortion.
US Legal size (215.9 × 355.6 mm, or 8.5 × 14 inches) is commonly used for legal documents, contracts, and some government forms in the United States. It's the same width as Letter but about 3 inches taller.
Tabloid (also called Ledger in landscape orientation) measures 279.4 × 431.8 mm (11 × 17 inches) — exactly twice the area of US Letter, similar to how A3 relates to A4. It's commonly used for newspapers, posters, and spreadsheets needing extra width.
You can, but since A4 is taller and narrower than Letter, the content may be cropped at the bottom or have extra blank margin, depending on your printer's scaling settings. Most printers offer a 'fit to page' or 'scale to fit' option that adjusts the content to avoid cropping.
US Executive size (184.15 × 266.7 mm, or 7.25 × 10.5 inches) is a smaller format sometimes used for personal stationery, resumes, or executive correspondence. It's noticeably smaller than both Letter and A4.
The ISO 216 standard (which defines A4 and the rest of the A-series) was adopted internationally based on a mathematically consistent ratio, while the US continued using paper sizes that predate the ISO standard, based on older imperial paper-making conventions. Both systems remain in parallel use today depending on region.
A5 measures 148 × 210 mm (5.83 × 8.27 inches) — exactly half the size of A4. It's commonly used for notebooks, flyers, postcards, and booklets.
Also known as
A4 to letter sizepaper size chartISO paper sizesA4 dimensions in inchesUS letter size in mmA4 A5 size converterletter size to A4paper dimensions converterenvelope size converter