When it comes to large posters, the "A" sizes refer to standardized paper sizes commonly used in printing. For indoor and outdoor posters, especially those printed on polypropylene (polyprop), you'll need to select the appropriate size based on the visibility and location. Here's a guide to the relevant sizes:

Common Large "A" Paper Sizes:

1. A0

   • Dimensions: 841 x 1189 mm (33.1 x 46.8 inches)
   • Use: Suitable for large-scale posters, like billboards or large indoor displays, where maximum visibility is required.

2. A1

   • Dimensions: 594 x 841 mm (23.4 x 33.1 inches)
   • Use: Good for posters that need to be visible from a distance, both indoors and outdoors, such as at events, on shop windows, or on walls.

3. A2

   • Dimensions: 420 x 594 mm (16.5 x 23.4 inches)
   • Use: A more moderate size for posters that will be seen at a closer range. Suitable for indoor displays or outdoor posters in areas where people pass by more closely, such as on noticeboards or bus stops.

Outdoor Printing on Polypropylene (Polyprop):

• Polypropylene: This material is a durable, water-resistant plastic that is ideal for outdoor use. It can withstand weather conditions such as rain, UV rays, and wind, making it a popular choice for outdoor posters and signage.
• Considerations: When printing outdoor posters, you should ensure that the ink is UV-resistant to prevent fading and that the poster is laminated or treated to extend its lifespan against the elements.

Indoor Use:

• Indoor Posters: For indoor settings, you can choose uncoated or coated paper, but for high-traffic areas, polypropylene can also be beneficial as it is durable and resistant to tearing, making it ideal for longer-lasting displays.

Selecting the right size depends on the location and the impact you want to create. For maximum visibility, A0 is the largest and most effective, but A1 and A2 are also common choices depending on the space and viewing distance.