€21-34 for transport + museums in Naples, Pompeii, and the Campania region. Spoiler: it's excellent.
Plan your Italy trip →Napoli 3 giorni (€25): 3 days, Naples city only. 2 free museum entries + 50% off all subsequent + unlimited urban transport (metro, bus, funicular).
Campania 3 giorni (€34): 3 days, entire region. 2 free entries + 50% off all others + transport including Circumvesuviana to Pompeii/Herculaneum. This is the one most tourists want.
Day 1 Naples: Museo di Capodimonte (free, normally €12) + Napoli Sotterranea at 50% off (€5 instead of €10) + metro/bus all day (normally €4.50/day). Day savings: €16.50.
Day 2 Pompeii: Circumvesuviana train (free, normally €5.60 round trip) + Pompeii entry (free, normally €18). Day savings: €23.60.
Day 3 Naples/Herculaneum: Herculaneum at 50% (€6.50 instead of €13) + MANN archaeological museum at 50% (€10 instead of €20) + transport. Day savings: €16.50.
Total savings: €56.60 on a €34 card. The card essentially pays for itself on Day 1 and everything after is bonus savings.
Naples airport, Napoli Centrale station, major museums, online at campaniartecard.it. Activate at first use.