In detail
10 GB suits light users who are on Wi-Fi at home and at work and use mobile data mainly on the go: messaging, email, maps, a bit of social media and music. It covers about 3 hours of HD video a month, so one long train ride with Netflix can use a third of it.
What uses data is almost always video. In HD, 10 GB lasts about 3.3 hours; in SD about 14.3 hours; in 4K only about 1.4 hours. Everything else is light by comparison: 10 GB is about 67 hours of music streaming, and messaging, email and maps use only a few hundred megabytes a month.
For travel, 10 GB is a comfortable amount for one to two weeks of maps, messaging, ride-hailing apps and photo uploads, as long as you stream video on hotel Wi-Fi.
Spread over a month, 10 GB is about 0.3 GB per day; over two weeks it is about 0.7 GB per day. The calculator above shows how many days 10 GB lasts with your own mix of activities, and whether it's enough for a week, two weeks or a whole month.
To make 10 GB last longer, set video apps to data saver on mobile networks, download shows and playlists over Wi-Fi, turn off autoplay on social media and check which apps use background data in your phone's settings.