Notes
The Redbubble 3000px rule you read somewhere is not theirs
Search for Redbubble image requirements and you will find a confident "long edge of at least 3000px". It does not come from Redbubble.
What Redbubble actually publishes
Requirements are set per product, not per platform. The Graphic T-Shirt is 3873 × 4814. The Premium T-Shirt is 2875 × 3900. Stickers, cards and large-format items each have their own numbers. There is no single long-edge rule and no platform-wide DPI threshold in the documentation.
Two apparel products, two sizes
| Graphic T-Shirt | 3873 × 4814 px |
|---|---|
| Premium T-Shirt | 2875 × 3900 px |
Why a single number fails in both directions
Design to 3000px on the long edge and you are below what the Graphic T-Shirt asks for, while carrying more pixels than the Premium T-Shirt needs. A rule that is simultaneously too small and too large is not a useful rule. The per-product numbers are published; use those.
Frequently asked questions
Where do these per-product numbers come from?
Redbubble's own Dimensions & Format documentation lists them. Because they change as products are added and revised, check the current page before a launch rather than relying on a number from a guide.
What should I build to if I am publishing across many products?
Build a master at 4500 × 5400 and scale down per product. That covers every Redbubble apparel size with room to spare and stays consistent with what the other platforms need.