The DPI Math That Sinks Most Listings
Print providers want 300 DPI at the physical print size. A 12 by 16 inch shirt print area needs 3600 by 4800 pixels, and an 18 by 24 poster needs 5400 by 7200. Most designs fail that math because they were made for screens: a 1080 pixel social graphic, an AI generation at 1024 square, a logo exported for the web years ago. Printful and Printify warn you. Redbubble prints it soft, and the one-star review arrives with a photo to prove it.
Upscale to Spec Without Changing the Design
For print-on-demand, fidelity is the priority: your typography, brand colors, and layout must arrive at the printer exactly as designed. The faithful model multiplies resolution while keeping edges crisp and colors true. A weak source, an old low-res design or an AI generation with mushy detail, is a different job; the AI art workflow covers that path. Transparent PNGs keep their alpha channel with either model, so apparel cutouts stay clean.
Settings That Work
- Model: any faithful model; P Image Upscale is the default in the upscale tool
- Scale: enough to reach 300 DPI at the largest product the design will ever be on
- Enhance Faces: off for artwork
- Output: PNG, so transparency and flat colors stay lossless
Make It a Catalog Habit
Successful sellers standardize the step: every design that enters the catalog gets upscaled to a master file large enough for the biggest product it will ever appear on, then downscaled per product. Batch processing makes the backfill of an existing catalog practical, and one-time credits fit the bursty rhythm of design drops. Verify print sharpness on one design first with the free no-signup upscaler.
