What uses the most mobile data?
Video, and then everything else a long way behind. But the interesting part is what happens without you asking it to.
In order, roughly per hour
These are typical figures. Every one of them has a real range around it, which is the point of the next section.
4K video — around 7 GB an hour. An hour of this can use more than a week of everything else combined. Very few phone screens show any benefit from it at all.
HD video — roughly 1.5 GB an hour. The default on most services when the connection looks fast enough to support it, which on 5G it usually does.
Video calls — 0.3 to 1.6 GB an hour. A one-to-one call on a messaging app sits near the bottom; a group meeting in HD sits near the top.
Standard-definition video — around 0.5 GB an hour.Roughly a third of HD, and on a phone held at arm’s length the difference in what you see is much smaller than the difference in what you pay.
Tethering a laptop — 0.15 to 1.5 GB an hour. Entirely decided by what the laptop does, including its own updates in the background.
Social media — 0.08 to 0.35 GB an hour. Almost entirely decided by autoplaying video. A feed of text and photos is a fraction of a feed of clips.
Music streaming — 30 to 145 MB an hour. Follows the bitrate directly: about 43 MB an hour at 96 kbps, 72 at 160 kbps, 144 at 320 kbps.
Browsing — 30 to 120 MB an hour. Text-heavy pages at the bottom, image-heavy news and shopping at the top.
Maps and navigation — 2 to 15 MB an hour. Far smaller than people expect. Live traffic and re-routing account for most of it, not the map.
The two that are not activities at all
Ask somebody where their data went and they will describe things they did. The usage nobody can account for is usually two things the phone did on its own.
Photo and video backup.A single minute of phone video can be 100–300 MB. A weekend of filming children or a holiday, uploaded automatically over mobile data, is several gigabytes moved without a decision being made. This is the largest single avoidable item on most phones.
App updates and background refresh. Individually small, collectively substantial, and completely invisible. Both platforms let you restrict them to Wi-Fi.
If your allowance disappears and you genuinely cannot say where, start with those two rather than trying to remember how much video you watched.
Why the ranges are as wide as they are
Quality is adaptive. Most video services pick a quality based on how fast the connection looks. A good 5G signal makes them choose a higher bitrate, so the same programme uses more data than it would on a weaker connection. Faster is not free.
Compression differs. Newer codecs deliver the same picture in materially less data, and which one you get depends on the service, the device and the content.
Autoplay changes everything.The difference between a social feed that plays video automatically and one that does not is most of that activity’s range.
This is why our mobile data calculator gives a band rather than a figure. The uncertainty is real, and stating it is more useful than hiding it behind a decimal point.
What this means for reducing it
The order above is also the order in which changes are worth making. Anything you do to navigation, music or browsing is noise; the whole of a month’s music streaming can be less than one film in HD.
Video quality and backup are where the data is, and both are settings rather than sacrifices. How to reduce mobile data usage goes through them in order.