The honest answer is that it depends on one thing: whether you watch video on mobile data. Everything else on your phone is a rounding error next to it.
What each thing actually costs
| Activity | Roughly | Per hour |
|---|---|---|
| Maps and navigation | 3–5 MB per 30 minutes of driving | ~10 MB |
| Messaging (text, photos) | under 1 MB per message with a photo | ~10–20 MB |
| Web browsing and search | 1–3 MB per page | ~40 MB |
| Social feeds (scrolling) | heavy on autoplay video | ~150–250 MB |
| Music streaming | depends on quality setting | ~60–150 MB |
| Video calls | the quiet budget-killer | ~300–500 MB |
| Video streaming (HD) | the loud budget-killer | ~1.5–3 GB |
Read that table once and the strategy becomes obvious. Navigation for a whole day of sightseeing costs less than five minutes of HD video. If you are rationing data, ration video — not maps.
A per-day estimate you can trust
- Light — around 200 MB/day. Maps, messaging, the occasional search. Photos backing up on Wi-Fi only.
- Normal — 400–700 MB/day. The above, plus social feeds, music on the move, a few video calls home.
- Heavy — 1.5 GB+/day. Video streaming on mobile data, tethering a laptop, or working remotely.
Multiply by trip length, then add about 20% for the things you cannot predict — a delayed flight spent online, a hotel whose Wi-Fi does not work, an evening of navigating a city you got lost in.
| Trip | Light | Normal | Heavy |
|---|---|---|---|
| Long weekend (3 days) | 1 GB | 2–3 GB | 5 GB+ |
| One week | 2 GB | 3–5 GB | 10 GB+ |
| Two weeks | 3 GB | 5–10 GB | unlimited is simpler |
The three settings that halve your usage
- Download offline maps before you fly. Google Maps and Apple Maps both do this. Navigation then costs almost nothing and works in a metro station.
- Turn off autoplay video in your social apps. This is the single biggest saving available and you will barely notice it.
- Set photo backup to Wi-Fi only. A week of holiday photos syncing over mobile data is gigabytes you did not choose to spend.
When unlimited is the right answer
Buying a fixed allowance means thinking about it. Some trips are not worth thinking about: a working trip where you will tether a laptop, a long trip where the arithmetic gets tiresome, or travelling with someone who will absolutely watch video on the train. An unlimited plan removes the decision, and for trips longer than about a week it often costs less than the equivalent stack of top-ups.
One thing to check on any unlimited plan, ours included: most apply a daily high-speed allowance, after which speeds reduce until the next day. That is fine for messaging and maps, less fine for video. The plan page states the daily cap for each option.
If you get it wrong
Running out is not a crisis. You can top up an existing eSIM without reinstalling anything or losing the plan you already have. Running out is also, in fairness, cheaper than habitually buying twice what you need.
