A4 paper

A4 paper measures 8.27 inches (210 mm) wide and 11.69 inches (297 mm) tall. It is the standard paper size used for everyday printing, office documents, and correspondence in almost every country except the United States, Canada, and a handful of others that still use Letter size. This page covers the exact dimensions, how A4 fits into the ISO paper system, and how it compares to US Letter.

Dimensions

Area and aspect ratio

A4 has an area of 0.0625 square meters, exactly one-sixteenth of a square meter. Its aspect ratio is 1:√2 (about 1:1.414), which means folding an A4 sheet in half produces two A5 sheets with the same proportions. This ratio is what makes the entire A-series scale so cleanly.

The ISO 216 A-series system

Each size in the series is exactly half the area of the one above it, cut along the long dimension. A3 folded in half makes two A4 sheets. A4 folded in half makes two A5 sheets. This is why A4 paper fits perfectly into an A5 envelope when folded once, and why A3 posters can be printed as two A4 pages and taped together.

A4 vs US Letter

A4 is narrower and taller than US Letter. The difference is small but enough to cause printing problems when a document formatted for one size is printed on the other. Text near the bottom of a Letter-formatted document can get cut off when printed on A4, and A4 documents printed on Letter paper often have extra white space at the bottom with slightly narrower margins on the sides.

Common uses

A4 is the default paper size for printers, copiers, and word processing software across most of the world. Business letters, reports, forms, contracts, and school assignments in Europe, Asia, Africa, Oceania, and most of Latin America use A4 as the standard. Ring binders, folders, and filing cabinets outside North America are sized to hold A4 sheets.

Practical tips for working with A4

When setting up a document in software like Microsoft Word or Google Docs, check the page size setting before you start, since many US-made templates default to Letter size. If you are shipping printed materials internationally, confirm which size the recipient’s printers use. A PDF set to A4 will print with slight margin differences on a Letter printer unless you select “fit to page” in the print dialog, which can slightly shrink or crop the content.

Frequently asked questions

What is A4 paper size in inches?

8.27 x 11.69 inches. In millimeters, it is 210 x 297 mm.

Is A4 the same as Letter size?

No. A4 is 210 x 297 mm and US Letter is 216 x 279 mm. A4 is narrower and taller than Letter.

How many A4 sheets make an A3 sheet?

Two. A3 is exactly twice the area of A4, and folding an A3 sheet in half produces two A4-sized sheets.

Why does the US use Letter instead of A4?

The US, Canada, and a few other countries kept their own paper standard that predates the ISO 216 system, which was adopted internationally starting in the mid-20th century. Letter size has remained the default in North America ever since.

Can I print an A4 document on a US printer?

Yes, but most US printer trays default to Letter paper. You will need to load A4 paper manually or select “fit to page” when printing, which may slightly scale the content.

Related objects

• A3 paper
• A5 paper
• US Letter paper
• US Legal paper