Full guide
Notes on print files
Each of these answers one question, and each is built on a number we have checked against the platform that publishes it. No general design advice.
All notes
Why gradients and grain double your PNG file sizePNG compression scans for predictable patterns. Flat colour compress…What actually costs the most bytes in a transparent PNGAlpha is a fourth channel that compresses by the same rules as colou…What happens when Printify enhances a low-resolution filePrintify does not reject a low-resolution design. It enhances the pr…Vector vs raster: what survives a garment size runPrintful scales a design across garment sizes, so one file prints at…One master file for all four platformsBuild once at 4500 × 5400, 300 DPI, sRGB, transparent PNG. That is 1…The Redbubble 3000px rule you read somewhere is not theirsRedbubble publishes a different minimum pixel size for each product.…Printful has no published rejection line — what that means for youPrintful documents a recommended density of at least 150 DPI, and no…sRGB or CMYK: which one print-on-demand actually wantsPrint uses CMYK ink, so designers reasonably assume print files shou…