International Standard Paper Sizes · Daring Fireball
Science, Technology & Innovation · Sep 26, 2026
ISO 216 uses a √2 aspect ratio and halving-based A-series sizes to make scaling predictable, preserve layouts, and simplify printing operations, material calculations, and equipment standardization. An A4 sheet has an area of 1/16 m² and weighs 5 g at 80 g/m²; A3-to-A4 reduction uses 71% scaling and yields two A5 pages without cropping.
International Standard Paper Sizes · Daring Fireball
Science, Technology & Innovation · Sep 26, 2026
The text explains that incompatibility between North American paper sizes and ISO A4 can create margins, require 94–97% scaling, alter pagination, and cause information loss or reformatting; it recommends A4 as the default for international software and document workflows.
International Standard Paper Sizes · Daring Fireball
Business, Finance & Industries · Sep 26, 2026
ISO B and C paper sizes extend A-series dimensions using geometric means to create interoperable intermediate formats and envelope sizes, supporting coordinated design across paper, packaging, equipment, and scaling workflows; internationally sourced products should distinguish ISO B from Japanese JIS B sizes, which use arithmetic means and are not equivalent.