Rough monthly guides
Light use — messaging, maps, email and some music — usually lands between 2 GB and 5 GB a month.
Moderate use with daily social media and occasional video is typically 10 GB to 20 GB.
Heavy use, streaming video on mobile data daily or tethering a laptop, is where unlimited plans start to earn their price.
Wi-Fi changes everything
If you are on Wi-Fi at home and at work, your mobile data need is usually a fraction of what carriers assume.
Downloading playlists and maps over Wi-Fi before you travel can cut monthly usage substantially.
What happens when you run out
Capped plans usually slow to around 2G speeds rather than charging overage, which is usable for messaging but not video.
Unlimited plans have a high-speed threshold too — after it, you may be deprioritised when the local tower is busy.
This guide is general information, not advice about a specific account. Always check current terms on the carrier’s own website before signing up.