The difference between A4 paper and US letter size paper

The specification and size of paper used may vary in different countries. A4 paper is a common paper format that is widely used in many countries, while the United States uses a unique letter size paper.

Here are the differences between A4 paper and US letter size paper:

1. Size difference
The standard size of A4 paper is 210 mm×297 mm (8.27 inches×11.69 inches), and the aspect ratio is 1:√2. This is a longer and narrower paper size suitable for printing documents and books.
In comparison, the standard size of US letter size paper is 216mm x 279mm (8.5 inches x 11 inches), with an aspect ratio of 1:1.294. Paper of this size is closer to a square and is often used to make envelopes or other letter paper.

2. Paper usage
A4 paper is widely used in printing, copying, writing and document archiving and other occasions. Its long and narrow shape gives it certain advantages when arranging documents, especially for making books and documents arranged vertically.
In contrast, US letter size paper is mainly used for writing letters, making leaflets and announcements, etc. Its more square shape makes folding and stapling easier, and it fits easily into standard envelopes.

3. Geographical differences
A4 paper is one of the international standard paper specifications and is widely used in Europe, Asia and most other regions. Therefore, in most countries, including China, A4 paper is the most common and easily available paper size.
US letter size paper is most commonly used in and around the United States. This paper format is not commonly available in other regions.
Although there are some differences between A4 paper and US letter size paper, both have their own characteristics and applications. When choosing paper, it should be selected according to the required use and the actual situation in the area. No matter which paper you choose, the key is to make sure it is of good quality and meets your needs for printing, writing or conveying letters.