The Redbubble Artwork Upload size (3000×3000px)
Redbubble recommends uploading artwork at a minimum of 3000x3000 pixels because a single design gets printed across dozens of products at wildly different scales, from a two-inch sticker to a large wall print. Uploading one high-resolution 3000x3000 file gives Redbubble's system enough pixels to apply your art cleanly to whichever product a customer chooses, without the blur or pixelation that a small source would produce on the bigger items.
The square 1:1 ratio is a practical default for print-on-demand because it centers well on apparel, phone cases, and stickers, and it gives you predictable placement in Redbubble's product previews. Many artists design at 3000x3000 or larger with a transparent PNG background so the same file works both on light and dark garments and floats correctly on products where the background shows through. Getting the resolution right once means you are not re-exporting a dozen variations later.
Because your income depends on print quality, resolution is not a place to cut corners: a 3000px file keeps line work crisp and colors clean even when scaled up for a poster or duvet cover. Redbubble may reject or poorly render low-resolution uploads, so hitting the recommended size protects your catalog. Everything here resizes 100% in your browser with no upload and for free, so your original artwork never leaves your machine. Redbubble's upload guidelines and per-product requirements change over time, so verify the current recommendation before publishing a design.