Background Data: What Your Apps Send When You Are Idle
A phone sitting on a table is not doing nothing. We put four handsets behind a logging proxy for a week and counted every connection made while nobody touched them.
Tech Daily Review Desk
The shift
Background data stopped being a trickle. Applications now sync, prefetch, report and refresh on schedules of their own, and the operating systems that were supposed to rein this in have mostly settled for asking users to approve it once, in a dialogue, during setup.
Two different things get called background activity. One is work you asked for — a messaging app fetching messages, a mail client checking mail — and it is why the phone is useful. The other is telemetry, advertising identifiers and analytics, which is work the application does for somebody else. They look identical from the outside, they are billed to the same allowance, and the only way to tell them apart is to look at where the connection goes.
Why it matters
Because it is your battery, your data allowance and your information, and all three are spent while the screen is off and nobody is watching.
Our method
Four handsets, freshly set up with the forty most-installed applications and then left untouched on a desk for seven days, with all traffic through a logging proxy holding its own certificate. We counted connections, bytes and distinct destination hosts, and classified each host as first-party or third-party by its registered domain. Nobody opened an app during the week.
The measurements
| Category | Connections a day | Data a day | Distinct hosts | Third-party share |
|---|---|---|---|---|
| Messaging | 412 | 2.1 MB | 6 | 4% |
| Social | 1,847 | 31.4 MB | 71 | 68% |
| News and media | 906 | 18.2 MB | 94 | 81% |
| Shopping | 634 | 9.7 MB | 58 | 77% |
| Games, none opened | 288 | 4.1 MB | 41 | 92% |
| System and OS services | 521 | 6.8 MB | 11 | 0% |
| All forty apps | 4,608 | 72.3 MB | 281 | 64% |
Reading the results
Seventy-two megabytes a day from a phone nobody touched — a little over two gigabytes a month, before anybody uses it for anything.
Two thirds of the connections went to somebody other than the company whose app it was, and games nobody had ever opened were the worst offenders at 92%.
Messaging was the cleanest category by a wide margin, which makes sense: it has a job and the job is the connection.
Restricting background data on the ten worst apps cut the total by 61% in a follow-up week and broke nothing anybody noticed.
Where this could mislead you
Three things worth holding on to when you meet these figures somewhere else:
- A permission prompt at install says nothing about how often, or to whom — the frequency is never part of the question
- "background app refresh" and "background data" are different switches on most phones, and turning off one leaves the other running
- The figures scale with how many apps you have installed rather than how many you use, so the fix is often uninstalling rather than configuring
What we would buy
Go through the background data permission list once and restrict anything you would not miss. The honest test is whether you need it to tell you something the moment it happens: messaging and mail pass, a shopping app and a game do not. In our follow-up week that single pass removed nearly two thirds of the traffic with no effect anybody could detect.
Uninstall rather than configure where you can. An application you opened twice last year is generating this traffic every day regardless of your settings, and the figures above are per installed app, not per used one. The games we had never opened were the single worst category in the whole dataset.
The bottom line
About two gigabytes a month from a phone nobody is using, two thirds of it to third parties. One pass through the background permission list cut ours by 61% and broke nothing.
Behind this piece
Every product covered here was bought at retail and lived with for at least a fortnight before a word was written. Battery figures come from a scripted day rather than a manufacturer estimate, and sustained performance is measured warm — after half an hour of load — because that is the state a device spends most of its life in.
Where a firmware update changes a result, the piece is re-tested and the change noted rather than quietly corrected. No review unit arrives with conditions attached, and no score is agreed in advance with anybody.
Where to go next
If you are weighing this against the rest of the smartphones we have covered, the category archive lists every review in date order. The closest comparisons we have published are Charging to 80 Per Cent: What It Is Actually Worth and Display Brightness Claims Against a Meter.
For the reference material behind these figures, the specification pages carry the measured numbers, and the common questions collect what people ask once something is in daily use.
