The maximum file size depends on what you're uploading:
- Artwork files (JPEG, PNG, TIFF): 2 GB (files this large are rarely necessary, so keep well under this where you can).
- Signature files (PNG or JPEG): 10 MB
- Letter inserts (A4 PDF): 25 MB
There's a minimum too
Files below 2 megapixels are rejected with a prompt to upload a higher-resolution version. A rejected file stops that image's order journey with the specific reason shown — it won't continue silently on a broken image.