See our File uploads FAQ for more details about how file uploads work.
All files uploaded to a GPT or a ChatGPT conversation have a hard limit of 512MB per file.
All text and document files uploaded to a GPT or to a ChatGPT conversation are capped at 2M tokens per file. This limitation does not apply to spreadsheets.
For images, there's a limit of 20MB per image.
Additionally, there are usage caps:
Each end-user is capped at 10GB.
Each organization is capped at 100GB.
Note: An error will be displayed if a user/org cap has been hit.