Most travellers buy far more data than they use, or far less. The fix is simple: estimate by the hour, not by the day.
What uses data, per hour
These are typical figures. Video quality matters most: one hour of HD video can use as much as four hours of SD.
Three kinds of traveller
These are for a two-week trip with hotel Wi-Fi in the evenings. Without Wi-Fi, roughly double them.
Save data without trying
Download maps and playlists on Wi-Fi before you go. Set photo backups to Wi-Fi only. Turn off autoplay for videos in social apps.
Still unsure? Pick the smaller plan. You can top up the same eSIM anytime, so you never pay for data you do not use.