The best poster size is determined by where people will see it and how far away they will stand. Design for quick reading first: a simple hierarchy is usually more useful than squeezing in every detail.
UK campaign print reminder
This guide is designed for UK print buyers. It does not replace election, advertising, planning or legal advice for a particular location, election or campaign.
A4 for close viewing
A4 measures 210 × 297mm. It works well in windows, on compact noticeboards and at tables where viewers can stand nearby. It gives space for a clear name, message and contact detail, provided the type remains comfortably readable.
A3 for stronger presence
A3 measures 297 × 420mm and is more visible in larger windows, campaign offices, meeting spaces and other approved display locations. It is a useful choice where people will encounter the poster from several steps away.
Plan for viewing distance
Use a large primary message, a smaller supporting line and a restrained amount of body copy. High contrast and a single focal point are easier to read than a dense layout. Review a PDF at the intended physical size before approving it.
Leave room for production details
Keep important text away from the trim edge, allow the specified bleed and include an appropriate imprint where required. Product specifications, stock and current dispatch options should be checked on the poster product page.