The right size depends on where the poster goes and how far away people will be when they read it. A poster that looks huge on the counter can look small in a wide window, and an A1 crammed into a narrow door panel just looks cramped.
A-sizes and where they suit
A5 (148 × 210 mm): tills, counters and tabletop notices, read from arm's length.
A4 (210 × 297 mm): doors and smaller displays, read from a step or two away.
A3 (297 × 420 mm): most shop windows and indoor promotional areas. A sensible default for a small frontage.
A2 (420 × 594 mm): medium storefronts where you want the offer readable from across the pavement.
A1 (594 × 841 mm): larger windows and stronger street visibility, read from further away.
Full dimensions in millimetres and inches are in our Poster Size Guide.
Viewing distance and headline size
Think about where the reader stands. Someone on the far side of the pavement needs a much larger headline than someone at your till. As a rough working rule, the headline and discount figure should fill a good part of the poster's width, and anything you want read from outside should be large and short.
The more text a poster carries, the closer people have to stand to read it. If a window poster needs a paragraph, it is doing a counter sign's job.
Window clutter matters more than size
A single A2 in a clear window often outperforms an A1 surrounded by stickers, old notices and stock. Before ordering, look at the window from across the street and decide what will come down. Leaving space around the poster is part of what makes it readable.
Portrait or landscape?
Portrait suits most door panels and tall window sections. Landscape works on wide, low windows or above a display. If your artwork was designed in a different shape, the Poster Resizer shows how much would be cropped or how wide the borders would be at each size.
Why bigger is not automatically better
A larger poster needs more pixels to stay sharp, and it needs space around it to work. If your file is small, a crisp A3 will look better than a soft A1. Posters seen from further away can print well at lower DPI than a close-up print, so you do not always need 300 DPI at large sizes. The Poster DPI Calculator shows the effective DPI of your file at each A-size, and our artwork help covers file formats and safe areas.
When you know the size, our Black Friday print studio has personalised and upload-your-own options from A5 to A1.