That means SRA4 has dimensions 5% greater than A4, SRA3 has dimensions 5% greater than A3, SRA2 has dimensions 5% greater than A2, and SRA1 has dimensions 5% greater than A1, etc. SRA paper sizes include an additional bleed area and have dimensions that are exactly 105% the size of the corresponding A-Series paper sizes. SRA stands for “Supplementary Raw Format A,” and these standard sizes are meant to be used for documents that are to be trimmed.
ISO 219 includes a series of RA and SRA paper sizes. The C-Series are also a bit wider than the A-Papers, which is why they are often used for envelopes: A-Series papers can easily slide inside of envelopes with C-Series dimensions. The B-Series has slightly wider dimensions, which makes them a great size for posters. ISO 219 also includes a B-Series and C-Series. While A-size paper is the most commonly used around the world, there are other paper sizes as well. Image by Wikipedia user Bromskloss, CC BY-SA 3.0 A chart showing how North American standards for paper sizes differ from the ISO A-series sizes. Most people wouldn’t perceive the difference in dimensions between standard US letter size paper and ISO A4 paper unless they were placed side by side. The differences are hardly noticeable to the naked eye. Standard paper sizes in the United States, however, do not have a consistent aspect ratio. A lifesize model demonstrating the square-root aspect ratio of ISO’s A-series paper standards in a museum in Barcelona. This means that the height and width relate to each other in the same way that the side and diagonal of a square do. ISO A-Series paper always has an aspect ratio of 1 to √2. That equals 8.27 x 11.7 when expressed in inches, which is a decidedly less user-friendly number.Īnother important difference between North American and international paper sizes is the aspect ratio. To compare, the closest ISO equivalent, A4 paper, measures 210 × 297 mm. Letter size paper in the USA measures an easy-to-remember 8.5 by 11 inches. Most importantly, North American standards are designed for the imperial measurement system rather than the metric system. There are several key differences between the paper sizes laid out in ISO 216 and those used in North America. What are the differences between ISO standards and North American standards? But the ANSI and ISO systems are the most common paper size standards around the world. And different countries have their own institutes responsible for developing norms. ISO 216 is the internationally recognized norm for paper sizes. In the rest of the world, the International Organization for Standardization, or ISO, presides over the regulation of paper sizing. The norm in which all standardized paper dimensions can be found is called ANSI Y14.1. In the United States, standard paper sizes are decided by the American National Standards Institute, or ANSI. Used primarily the in the United States, Canada, and the Philippines. A-Series International Standard Paper Sizes While most of the world uses the ISO 216 standard for paper sheet sizes, the North American system is slightly different and features dimensions that are easier to express in inches.Īt a glance, here are the ISO A-Series international paper sizes and the North American paper size standards. Standard paper sizes differ depending where you live. The standardization of paper sizes simplifies this process. Many objects need to be designed with the correct paper dimensions in mind. Envelope sizes, binders, printer trays, file cabinets, mail service, frames, documents – just to name a few.