How to reduce mobile data usage
Two settings account for most of it. Everything after those is diminishing returns, and it is worth knowing which is which before you start turning things off.
1. Set photo and video backup to Wi-Fi only
This is the largest single avoidable item on most phones and the one people least expect. A minute of phone video is 100–300 MB; a weekend of filming, uploaded automatically over mobile data, is several gigabytes moved without any decision being made.
Restricting backup to Wi-Fi changes nothing you would notice. Your photos still back up, a few hours later, when you are next on Wi-Fi. Every cloud photo service has this setting and most of them do not default to it.
2. Drop video quality on mobile data
Most video apps have a separate quality setting for mobile data. Moving from HD to standard definition roughly thirds the data an hour of video uses.
On a phone screen, held at normal distance, the difference in what you can see is far smaller than the difference in what you pay for. This is the single highest-value setting in the list relative to what you give up.
Worth checking on every video app separately — they do not share the setting, and the one you use most is the one that matters.
3. Turn on the built-in data saver
Android has Data Saver and iOS has Low Data Mode. Both stop background refresh, pause automatic downloads over mobile data, and ask apps to be less greedy.
This is the setting that catches the usage nobody can account for, because most of it is things the phone did while it was in a pocket.
4. Turn off autoplay in social apps
Autoplaying video is the difference between a social feed costing 80 MB an hour and 350. It is also the usage that feels least like a decision, because you did not choose to watch any of it.
Every major app has the setting, usually under something like “media and contacts” or “data usage”, and it can be set to Wi-Fi only rather than off entirely.
5. Download things at home instead
Music, podcasts, maps and episodes can all be downloaded on Wi-Fi and used offline. Offline maps in particular remove the activity most likely to run while you are out, and they work better than streaming ones when the signal is poor.
6. Restrict app updates to Wi-Fi
Individually small, collectively substantial, and completely invisible. Both app stores let you require Wi-Fi for automatic updates, and there is very little reason not to.
7. Watch what tethering does
A laptop connected to your phone behaves like a laptop, not like a phone. It will check for its own system updates, sync cloud folders and back things up, none of which it knows is happening over a metered connection.
If you tether regularly, set the connection as metered in the laptop’s network settings. Both Windows and macOS respect that and it stops most of the surprise.
What is not worth bothering with
Turning off music streaming, browsing less, or being careful with maps. The whole of a month’s music streaming can be less than one film watched in HD, and navigation is a rounding error — a two-hour drive costs about 10 MB.
Effort spent there is effort not spent on the two settings at the top of this page, which is where the data actually is. See what uses the most mobile data for the full order.
Set a warning, then check
Both platforms can warn you at a set amount of mobile data and cap you at another. Setting a warning a little below your allowance turns running out from a surprise into a prompt.
Then give the changes a month and look at the number again. If a month of this brings you comfortably inside a smaller allowance, that is a saving worth making permanent — the data calculator will show you which band you have landed in, and the contract cost checker what a smaller plan would actually cost over its term.