Do apps use data when I am not using them?

Yes. Many apps sync, download updates and back up photos in the background, which is a common reason an allowance disappears faster than expected. Turn off background refresh, disable automatic photo backup on mobile data, and set app updates to Wi-Fi only.

Many people notice their data allowance falling faster than expected, even though they remember opening only a handful of apps that day. Most of the explanation is not in the moments you actively use an app, but in what it keeps doing quietly in the background without you noticing. This page explains what uses data even when you are not looking at the screen, and how to check and control it on both iOS and Android.

This is written for a traveller who wants a plan to last the whole trip, and also for anyone who simply wants to understand why the usage figure keeps ticking up while the phone sits untouched on a table. There is no way to switch off all background data use with zero effect on how the phone behaves, but understanding what uses the most lets you turn off what you do not need while keeping what you still want.

Why an app you have not opened still uses data

Modern phones are built so apps keep working even when they are not on screen, so notifications arrive instantly, content is already up to date when you open an app, and photos or files are backed up automatically without opening that app at all. Every one of these uses data; it simply happens at a moment when you are not looking at the screen.

This is not a fault; it is a deliberate design choice that makes a phone feel fast and always ready. The problem appears once you are on a limited data plan while travelling, because the very same behaviour that is harmless at home on unlimited Wi-Fi quietly eats into an allowance instead, unnoticed.

The main categories that use background data

Checking and controlling it on iOS

iOS has both an overall setting for background refresh and a separate per-app switch for mobile data, and it is worth checking both, since they control different things.

1. 1Turn off background refreshGo to Settings, General, then Background App Refresh, and switch it off entirely or per app for the ones you do not need
2. 2Check mobile data per appGo to Settings, Mobile Service or Cellular, and scroll down to the app list to see which one uses unusually more than expected
3. 3Switch off mobile data for apps you do not need abroadTurn off the mobile data switch for that app so it only works while on Wi-Fi
4. 4Set photo backup to Wi-Fi onlyOpen the backup app and find its mobile data option, switching it off so backup happens only on Wi-Fi

Checking and controlling it on Android

Android allows finer control in some places, both at the system level and per app, though menu names vary slightly by manufacturer.

1. 1Turn on Data SaverGo to Settings, Network & internet, then Data usage, and turn on Data Saver, which restricts background use for most apps automatically
2. 2Check data usage per appOn the same screen, scroll through apps ranked by data used to spot anything unusually high
3. 3Disable background data for apps you do not needTap into that app and switch off background data so it only works while actively open
4. 4Set app updates to Wi-Fi onlyOpen the app store's own settings and set automatic updates to download over Wi-Fi only

Cloud sync and backup, explained

One of the most common causes is cloud backup: photos, video, contacts and documents. These systems are designed to work the instant a connection appears, without opening the app at all, which is convenient at home on unlimited Wi-Fi, but becomes a risk to a data allowance the moment you switch to mobile data.

Worth checking are both the operating system's own settings and each app's separate settings, since some apps have their own backup switch independent of the system one. Turning off only one place may not cover every route the backup can take.

App updates and system updates

Update files are usually far larger than ordinary activity, whether for an individual app or the operating system itself. Leaving automatic updates enabled over mobile data can produce a large, sudden drop in an allowance with no obvious cause at first glance.

• Set the app store to update only on Wi-Fi
• Set the operating system to download major updates only on Wi-Fi
• Postpone non-urgent updates until back at accommodation with Wi-Fi

Push notifications versus background refresh: the difference

The two are often assumed to be the same thing, but they behave differently. A push notification usually uses very little data, since it is just a short message announcing that something new exists. Background refresh is the app pre-fetching full content in advance, which clearly uses more.

Turning off background refresh does not mean notifications stop arriving; most still come through as normal. What changes is that full content is not pre-fetched until you open the app yourself, which can make it load a little more slowly at that moment, in exchange for a real saving in background data.

How this specifically affects your eSIM allowance

Most travel data plans carry a fixed amount for the whole trip, so unintended background use eats into that allowance without giving you any extra benefit, since you may never even look at the content that was fetched. Managing this before travelling is the most direct way to make a purchased allowance last the whole trip.

Data saver features that help

Both iOS and Android offer a mode that limits background data use broadly without switching off every app one by one, which suits anyone who does not want to go through the list individually or worry about forgetting to turn things back on at home. Though named and positioned differently, the principle is similar: it reduces apps' general permission to work in the background.

Do not switch off everything: what to keep

Restricting background data does not mean switching everything off entirely. Some of it is still useful while travelling, such as a map app syncing its last known position, or notifications from an app you use to coordinate with fellow travellers. Blanket disabling can mean missing something important at the moment it actually matters.

Checklist before you travel

1. Turn off automatic photo and video backup on mobile data
2. Disable background refresh for apps that do not need to be instantly current
3. Turn off automatic media download in chat apps
4. Set the app store and the operating system to update over Wi-Fi only
5. Turn on the operating system's data saver mode
6. Check the data usage screen at least once a day during the trip

Read more ways to save data while travelling

Estimate how much data your trip needs