Understanding Paper Sizes: What Exactly is 'A4', or 'A5'?

Navigating through the various paper sizes can be confusing, especially when you're trying to choose the right one for your needs. In this article, we'll break down the meaning behind common paper sizes like A4, A5, and A6, explaining their dimensions, uses, and how they compare to each other. We'll also explore how folding larger sizes results in smaller sizes within the same series.

The A-Series Paper Sizes

The A-series paper sizes are part of an international standard (ISO 216) used globally, except in North America and parts of Latin America. These sizes are based on a single aspect ratio of √2:1.

But why such a weird looking ratio? The primary benefit of this ratio is its ability to maintain the same aspect ratio when the paper is folded in half or scaled up or down. When you fold an A4 sheet in half, for example, along its longer side, the resulting size (A5) retains the same √2:1 aspect ratio. This consistent scaling applies to all A-series sizes, making it easy to enlarge or reduce documents without altering their proportions. Folding an A-series paper in half along its longer side results in the next smaller size.

We usually start with A0 paper, which is Huge in size. If we fold this on its longer side, we get A1 paper. Note how folding the longer side means the shorter side now becomes the longer side for A1. If we continue folding by this rule, we get A2, A3, A4 and so on. A4 and A5 are the most commonly used paper sizes in the world.

Another thing to note is that people often confuse the numbering. Since 2 is bigger than 1, it's commonly misinterpreted that A2 is bigger than A1. This of course isn't true! The number simply denotes how many times A0 has been folded.

A-Series Sizes and Their Uses

1. A0

   1. Dimensions: 841 x 1189 mm (33.1 x 46.8 inches)
   2. Uses: Large posters, technical drawings, and flip charts.
   3. Who Uses It: These are very rarely used. Due to its substantial size, it is primarily used in professional fields that require large, detailed displays of information. Architects, Engineers, and Artists can end up using A0 sized papers, but even then, it is rare.
      
      

2. A1
   

   1. Dimensions: 594 x 841 mm (23.4 x 33.1 inches)
   2. Uses: Posters, diagrams, and large-format advertising.
   3. Who Uses It: Similar to A0, these sizes are rare too. Photographers, or students for projects and exhibitions might use these paper sizes.
      
      

3. A2

   1. Dimensions: 420 x 594 mm (16.5 x 23.4 inches)
   2. Uses: Posters, architectural drawings, and charts.
      
      

4. A3

   1. Dimensions: 297 x 420 mm (11.7 x 16.5 inches)
   2. Uses: Diagrams, large tables, and small posters.
      
      

5. A4

   1. Dimensions: 210 x 297 mm (8.3 x 11.7 inches)
   2. Uses: Standard letterhead, magazines, catalogs, and office documents.
   3. Who Uses It: Commonly used by professionals, students, and in office settings for printing and writing.
      
      

6. A5

   1. Dimensions: 148 x 210 mm (5.8 x 8.3 inches)
   2. Uses: Notebooks, planners, flyers, and smaller print jobs.
   3. Who Uses It: Ideal for students, journalers, and anyone who prefers a portable notebook size.
      
      

7. A6

   1. Dimensions: 105 x 148 mm (4.1 x 5.8 inches)
   2. Uses: Postcards, small notebooks, and pocket diaries.
   3. Who Uses It: Perfect for travelers, note-takers on the go, and anyone needing a compact notebook.

The B-Series Paper Sizes

While we focus on the A-series sizes in this article, it's worth mentioning the B-series sizes, which are also part of the ISO 216 standard. The B-series fills in the gaps between the A-series sizes. They are typically used for larger documents and books. Similar to the A-series, folding a B-series paper in half results in the next smaller size.

A B0 paper has a dimension of 1000 x 1414 mm (39.4 x 55.7 inches). Following the same rule of folding along the longer side, we get B1, B2 and so on.

Conclusion

Understanding paper sizes like A4, A5, and A6 can help you choose the right one for your needs. Whether you're printing documents, taking notes, or creating art, there's a paper size that's perfect for the job. Visit our store to find a wide range of notebooks in these sizes and discover the one that best fits your requirements.