Sizing an eSIM for a three-month stay
Data to plan for across 90 days at three levels of use, and which plan shape works out better at this trip length.
Quick answer
- For 90 days: about 91GB at normal use, 41GB if light, 193GB if heavy.
- The numbers come from a fixed formula plus a 15 percent buffer, not from measuring your own use.
How much data 90 days needs
The figures below take three levels of daily use, multiply by the number of days, and add 15 percent for app updates and photo backup — the two things travellers forget.
| Level of use | Roughly per day | Total for 90 days |
|---|---|---|
| Light: maps, chat, email | 0.4GB | 41GB |
| Normal: social, photos, short video | 0.9GB | 91GB |
| Heavy: streaming, video calls, hotspot | 1.9GB | 193GB |
The plan shape that fits this length
At 90 days we would start with a long-stay plan, or a local SIM, because that is where price per gigabyte and the risk of wasted data balance out. If your usage is uneven, weigh the top-up terms as well.
What people forget when sizing by days
Multiplying days by daily use gets you close, but real trips are lumpy. Day one is usually the heaviest — navigating, checking in, messaging home — while a day on a tour or a long transfer can use almost nothing.
- The first and last days run above average; keep that in mind
- Travelling as a pair on one hotspot means budgeting for two people, not one
- Turning off automatic photo backup over mobile data, and syncing on Wi-Fi instead, is the single biggest saving available
FAQ
When does the 90-day clock start?+
Most plans start counting at first connection to a network at the destination, not at payment — but some count from the purchase date. Check the activation-policy line on the plan page before buying weeks ahead.
Should I buy exactly 90 days or add a buffer?+
Add at least one day. Delays, layovers and the trip home routinely spill past midnight, and a plan that expires while you are still at the airport leaves you offline exactly when you need it.
Daily or fixed data at this trip length?+
At 90 days the deciding factor is consistency. Even daily use suits a daily plan, which caps the cost predictably. Spiky use — heavy some days, nothing on others — suits a fixed-data pool.