Very hard to say, depends on the articles and the field you're in. Rule of thumb I'd say around 250, but that can be several orders of magnitude off. (And just to be sure that's clear: that's for articles synced with Zotero file storage; there is no limit on the number of articles you can save locally with Zotero with a free account)
Thank you for the response, however I am not sure if I understood you well when you said 'that's for articles synced with Zotero file storage; there is no limit on the number of articles you can save locally with Zotero with a free account'
It would be really great if you could tell me the difference between the 2 and how it works.
Upgrade Storage
(And just to be sure that's clear: that's for articles synced with Zotero file storage; there is no limit on the number of articles you can save locally with Zotero with a free account)
It would be really great if you could tell me the difference between the 2 and how it works.
2. Data syncing to Zotero servers is free and unlimited.
3. File syncing (eg PDFs) is subject to your online file storage quota (300 mb free; extra storage is paid).
4. You should also have good backups of your library.
See:
https://www.zotero.org/support/sync
https://www.zotero.org/support/zotero_data#backing_up_your_zotero_data