A poster of your own design, printed by a commercial printer, costs a fraction of a shop poster and is exactly what you wanted. The catch is that commercial printers expect a print-ready file, and “print-ready” has a precise meaning. Get the four things below right and the file goes through first time.
Pick a real paper size
In Europe the poster sizes are the A-series: A3 (297 by 420 mm), A2 (420 by 594), A1 (594 by 841), A0 (841 by 1189). Each is exactly half the one above, so the proportion is always 1 to 1.414. Frames are sold in these sizes too, which is the main reason to stick to them. The 50 by 70 cm poster is the other common frame size and is close to A2 but not the same; design for the size you will frame.
Add bleed, and keep text away from the edge
Printers print on a larger sheet and trim to size, and the trim wanders by a millimetre or so. Bleed is the extra image you extend past the edge so the trim never shows white; 3 mm on every side is the standard. The opposite margin is the safe area: keep type and anything important at least 5 mm inside the trim, or a letter loses its edge. Any layout program sets bleed in the document setup; a photo editor does not, which is one reason not to design a poster in one.
Use vector type and a layout program
Type set in a photo editor is pixels, and at A1 those pixels are visibly soft. A layout or vector program keeps type as outlines that stay sharp at any size. Affinity Designer or Publisher (free from Canva since late 2025), Inkscape (free) and Canva all do this. Set the document to the final size plus bleed, place photos at their full resolution, and set the type in the program rather than pasting it in as an image.
Photos inside the poster follow the resolution rule from our print preparation guide: 150 pixels per inch at the printed size is plenty for a poster on a wall.
Export a PDF the printer wants
Commercial printers ask for a PDF, usually PDF/X-1a or PDF/X-4, with bleed included, crop marks optional, fonts embedded or converted to outlines, and colours in CMYK. The X-standards exist so that the file carries everything the printer needs; choosing one in the export dialog sets most of this automatically. Convert to CMYK only at export, and expect very bright screen colours (a neon green, an electric blue) to come back a little duller, because CMYK ink cannot reach them. Consumer poster services such as Myposter and PosterXXL are happier with a high-resolution sRGB JPEG and handle the conversion themselves.
Where to print it
For one poster, a consumer service (Myposter, PosterXXL, Cewe) prints on photo or poster paper and ships it rolled or flat. For ten or more, or for a specific paper weight, a commercial printer is cheaper per copy: Onlineprinters and WIRmachenDRUCK both take PDF/X files, print on 135 to 250 gsm stock, and ship across Europe. Their online preflight checks the PDF as you upload it, so a missing bleed or an unembedded font is caught before anything is printed.
A test print first
Before ordering a run or a large size, print one A3 at home or at a copy shop and pin it up. Type that looked fine on screen is often too small, and a photo that was cropped tight looks tighter on paper. The A3 costs almost nothing and catches the mistakes that an A0 makes expensive.