Working out how much data to buy for a trip
Start from your own recent usage, not a generic “GB per day” figure.
By Simvito · Published · Reviewed and updated
In this guide
Start with a comparable day
Your phone’s settings show mobile data use by app; note the period it covers. Pick days when you used Wi-Fi about as much as you will on the trip. A day at home on Wi-Fi won’t tell you how much navigation uses when you’re out.
Count navigation, messaging, photo uploads, video calls and any laptop hotspot separately.
Build a budget
- Multiply your daily mobile data by the number of days you need data.
- Add a reserve. For example, 0.4 GB × 7 days = 2.8 GB; adding 25% gives 3.5 GB.
- Choose an allowance at or just above that figure, with enough days for the whole trip.
Size a daily plan for your busiest day
The budget above is for the whole trip. With a daily plan, also check that your busiest day fits the daily allowance. How daily and total plans work explains the difference.
A week in Japan, worked through
Say a week in Japan comes to 3.5 GB. In the Japan eSIM catalogue, pick a total-data option of 4–5 GB lasting 7 days or more.
Watch usage during the trip
Check usage in your phone’s settings as you go; your phone’s count may differ from the operator’s. Some plans show usage in My eSIMs, which comes from the operator and lags behind. Some plans can’t show usage.
Some plans add data, some add days, and some can't be topped up; each plan says which. Top up from the eSIM in My eSIMs. There's nothing new to install.