Every October we see a run of custom Halloween orders: party posters, pet portraits in costume and a lot of AI-generated horror art. Most print well. The ones that do not usually fail for one of three reasons: the file is too small, the shape is wrong for the paper, or something important gets cropped off. All three are easy to check before you order.
Check the pixels, not the file size
What matters is the image's width and height in pixels. A 4 MB file can still be small if it is heavily compressed, and a large PNG can be tiny in pixel terms. Our Poster Print Quality Checker reads the dimensions on your device and tells you which sizes will print well. Nothing is uploaded.
Why 300 DPI is not always needed
300 DPI is the right target for prints you hold in your hand or see from a few inches away, like A5 and A4. Posters are viewed from further back. At A2 and A1 you are usually standing a metre or more away, and around 150 DPI looks sharp at that distance. That is why a file that seems too small for A1 at 300 DPI can still produce a good poster. The Poster DPI Calculator works out the effective DPI for any image at each A-size.
AI images and aspect ratio
Many AI tools export square images by default, often around 1024 pixels wide. A-series paper is not square: every size from A5 to A1 has the same ratio of about 1 to 1.41. A square image on A-size paper either gets cropped at the top and bottom or leaves empty borders. Horror art suffers here because the important detail, a face or a title, is often near the edge.
Generate in portrait if your tool allows it. Something close to 2:3 or 3:4 crops far more gently than a square. Our AI Artwork Print Checker shows exactly how much of your image will be lost at A-size.
A word on upscaling
Upscalers can help a small AI image reach A3 or A2, but they guess at detail rather than recovering it. Dark, textured horror art often upscales well. Faces, small text and fine linework are where you will notice the invented detail. Check the upscaled file at full size on screen before ordering, and if it looks soft or waxy there, it will look the same on paper.
Ready to print
Once the file passes, print your own poster and choose a size. For anything else, from colour to file formats, our artwork help page covers the details.