*Ci* replaces a place or a thing introduced by *a* (*vado a Roma → **ci** vado*; *penso al lavoro → **ci** penso*). *Ne* replaces a quantity or something introduced by *di* (*voglio due mele → **ne** voglio due*; *parliamo del film → **ne** parliamo*).
The rule in one line
Don't memorise lists of uses: look at the preposition you're replacing. A → ci. Di → ne. Almost everything follows from that, and the few leftovers are recognisable.
Vado a Roma → ci vado. Credo a quella storia → ci credo. Ho parlato del problema → ne ho parlato. Ho bisogno di tempo → ne ho bisogno.
Ci, the three jobs
Place: sei stato a Milano? Sì, ci sono stato. The most frequent use and the easiest to spot.
*Verbs built with a**: pensarci, crederci, riuscirci, tenerci. Non ci riesco (I can't manage it), ci penso io (I'll take care of it). Here ci* is welded to the verb and is learned with it.
*The ci in c'è**: c'è un problema, ci sono due persone*. Same particle, carrying the sense of presence in a place.
Ne, the three jobs
Partitive quantity: quante mele vuoi? Ne voglio tre. Italian requires ne where English says nothing at all — "I want three" alone is wrong.
*Topic, with di**: hai sentito del film? Sì, ne ho sentito parlare.*
Origin: sei stato in ufficio? Sì, ne sono appena uscito.
In the perfect tense the participle agrees with the quantity: quante ne hai mangiate? (of apples). It's a detail, but it's the tell that separates learners who studied Italian from those who half-absorbed it.
Related questions
What's the difference between ci vado and ci penso?
None, mechanically: both replace something introduced by *a* — a place in the first case, a thing in the second.
Why is it ne voglio due and not voglio due?
Because in Italian the number alone isn't enough: you need the particle pointing back at the thing being counted. It's obligatory, not optional.
Updated 2026-07-29