post

In printing, a post is a standardized paper size of 19.25 inches by 15.5 inches (489 mm by 394 mm). It occupies the middle ground between smaller commercial sheets and the larger double crown format, making it practical for posters, announcements, and display printing where visibility matters but press capacity remains reasonable.

The post size emerges from the traditional Imperial paper sizing system, which grouped sheets by job function rather than pure mathematics. A post could be cut from larger parent stock or run directly on equipment built to handle its dimensions. The name itself reflects historical printing vocabulary, where different sheet sizes were given names tied to their end use: foolscap, demy, crown, and post each served distinct purposes in the trade. The post occupied a specific niche in this taxonomy.

A single post sheet provides enough area for a substantial visual message, roughly 300 square inches, without requiring the largest presses or the excessive paper waste that comes from cutting down oversized stock. This made it economical for runs of posters for shops, offices, and public spaces through much of the twentieth century. The format also accommodates standard text widths with modest margins, useful when posters needed to carry detailed information alongside graphics.

Decline and regional persistence

The post size has largely faded from active use in offset and digital printing, displaced by the ISO A-series metric standard (A2 at 420 mm x 594 mm serves similar purposes today). However, the measurement still appears in older specification sheets, in regions where Imperial sizing remains embedded in equipment design, and in specialty houses that maintain letterpress or offset machinery calibrated to traditional formats. Understanding what a post is remains necessary when inheriting legacy print jobs or sourcing compatible stock.

When someone references a post in a contemporary print specification, clarify whether they mean the exact 19.25 x 15.5 inch Imperial standard or whether they are using the term loosely to indicate a mid-sized display format. The ambiguity has grown as the term has fallen out of standard practice, making documentation essential for order accuracy.