Already rejected
The upload passed and it still printed blurry
This is the expensive failure: the platform accepted it, the sale went through, and then a customer opened a soft print.
The problem lives between "warning" and "rejection"
Only one of the four publishes a genuine rejection threshold. Merch by Amazon refuses anything that is not exactly 4500 × 5400. The other three document a recommended density and stop there — Printful says at least 150 DPI, Printify says 300, Redbubble says under 200 DPI is unlikely to satisfy customers. None of them tells you where the refusal line sits, because for practical purposes there is not one. A file below every recommendation still uploads, still lists, and still sells.
Batch, auto-fix and exports
Checking one file at a time is free and always will be. Batch checking up to 100 files, one-click exports sized for every platform, and CSV reports are part of Seller.
Exports are padded and centred to each platform's size on a transparent canvas. Nothing is ever upscaled — a file enlarged to pass a dimension check still prints soft, which is the failure this tool exists to prevent.
Three causes that have nothing to do with DPI
- The background is baked into the pixels — it looks white but it is opaque white, and it prints as a box on a dark garment.
- Downscaled then re-enlarged — shrunk to clear a size ceiling, then blown back up to the required dimensions. The size check passes; the information is gone.
- Large-format products — the same file is crisp on a sticker and mush on a tapestry. On Redbubble the high-margin categories are exactly the large ones.
Frequently asked questions
Why does it look sharp on my screen?
Typical displays run between 100 and 220 PPI while print needs around 300 DPI. Screen density is far lower, so a monitor preview cannot represent the printed result.
How do I catch this before publishing?
Judge by effective print DPI rather than by the on-screen preview. The tool on this page computes it against each platform's print area.