It depends on how you'll use your phone.
As a rough guide:
- 5 GB suits light use over about 1-2 weeks (maps, messaging, some social media);
- 12–20 GB suits a 2–4 week trip with regular social media, video calls and browsing;
- 30–50 GB suits longer stays, hotspot use, or heavy streaming and video calls.
You can always buy a new eSIM if you run out of data.