a3

A3 is an alphanumeric designation used in a variety of contexts, often referring to size, model, or route. Its meaning depends on the domain in which it appears.

A3 paper size is the most widely recognized use in office and publishing contexts. It is part of the ISO 216 standard and measures 297 by 420 millimeters. A3 is derived from halving A2, which in turn comes from halving A0, in the international A-series of paper sizes. It is commonly used for diagrams, drawings, posters, and larger spreadsheets, with A4 being the smaller, more common size for documents.

In the automotive world, the Audi A3 is a compact car produced by the German automaker Audi since 1996. It is available in several body styles, including hatchback and sedan, and is built on the Volkswagen Group MQB platform. The A3 line has included high-performance variants such as the S3 and RS3. Over successive generations, the A3 has broadened to offer a range of petrol, diesel, and hybrid powertrains, emphasizing efficiency and refinement within the premium compact segment.

A3 also designates major roadways in several countries. For example, in the United Kingdom the A3 is a primary trunk road running from London to Portsmouth, passing through suburban and rural areas. Other countries use the A3 designation for different highways or motorways, with the specific route and characteristics varying by nation.

Beyond these, A3 appears in various other contexts as a general size or model label. The exact interpretation is determined by the field and jurisdiction involved.