Posters are more forgiving than flyers, because nobody reads them from six inches away. Here's how far a ChatGPT image actually stretches.
The 300 DPI rule is for things held in your hand. A poster is read from across a room, where the eye can't see detail that fine. A 24 × 36 poster looks sharp at about 53 pixels per inch from where people stand to read it.
| Poster | ChatGPT tall gives (PPI) | Sharp needs (PPI) | Ask for (px) | Result |
|---|---|---|---|---|
| Tabloid – 11 × 17 in | 90 | 113 | 1,243 × 1,921 | SOFT |
| 12 × 18 in | 85 | 106 | 1,272 × 1,908 | SOFT |
| Poster – 18 × 24 in | 56 | 76 | 1,368 × 1,824 | SOFT |
| Large poster – 24 × 36 in | 42 | 53 | 1,272 × 1,908 | SOFT |
ChatGPT's tall images are 2:3, and so are 12 × 18 and 24 × 36 posters. Those print edge to edge with nothing cut off. 18 × 24 and 11 × 17 are a different shape, so either a strip gets cropped or there are white bars.
Soft means it prints, but small text looks fuzzy up close. Big headlines usually survive; the fine print doesn't. Regenerate at the pixels in the "ask for" column, or have PrintSanity redraw it at print resolution for $2.99. Upscaling is a gamble on anything with words: here's why.
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