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

Measure your own background usage before guessing

Advice about switching off background activity is usually told as a fixed recipe, when in reality the numbers differ enormously from person to person. A phone with ten messaging apps and a phone with three do not consume the same background data, and someone with automatic photo backup switched on lives in a different world from someone who turned it off long ago. Rather than trusting an average from who-knows-where, the way to get an answer that matches your actual handset is to measure it yourself for a day before you travel.

Measuring needs no special tool. Both operating systems already keep a data counter, and both give you a way to reset it. What it does need is the discipline not to use the phone unusually during the measuring window, because if you drift into half an hour of video, the number you end up with is no longer background data at all.

1. 1Pick an ordinary dayDo not pick a day when you plan to binge a series or sit in video calls from morning to night. Pick an ordinary day that resembles the way you will live while travelling, because the point is a number you can forecast a trip with.
2. 2Switch Wi-Fi off for the whole dayIf the phone stays on Wi-Fi, most background traffic runs over Wi-Fi and the mobile data counter barely moves, which leads you to conclude your phone is frugal when abroad there will be no Wi-Fi to lean on all day.
3. 3Reset the mobile data counter in the morningThe menu that resets it sits in a different place on each manufacturer and each OS version; broadly it lives in the settings screen about networks or data usage. Note the time you reset, so you know how many hours the number you later read actually covers.
4. 4Live normally, then read the counter at nightBefore bed, open the per-app breakdown and see which three apps sit at the top. That matters more than the total, because it tells you what to switch off first.
5. 5Repeat for one more day after adjustingAfter switching off background refresh for the apps at the top of the list, reset the counter and measure another day. A clear drop means you found the right culprit. No drop at all means the culprit is elsewhere, such as photo backup or a system update.

The first hour after switching the eSIM on is the heaviest

Plenty of people land, switch the eSIM on, and watch a chunk of the allowance vanish before they have done anything. The explanation is not complicated. While you sat on the plane for hours, every app on the device stopped syncing. The moment internet returns, they all rush to catch up at once: mail that arrived mid-flight, group chat backlogs, photos queued for backup, and the app store checking for updates.

The fix that works is to control the order. Do not let everything wake at once. Switch the eSIM's cellular line on first, wait for a network name to appear, then open only the apps you genuinely need in that minute, such as maps or a ride-hailing app. Leave the photo backup app and the app store switched off until you reach hotel Wi-Fi.

Background data that is not app refresh at all

The phrase background refresh makes people imagine one switch that ends the matter. In truth a single phone runs several kinds of background work, each living in a different place with its own switch. If you flip one and still see data flowing, that is not because the switch failed; it is because several other routes are still open.

Dual SIM is where this trips people up most

Once a phone carries two lines at once — your home SIM and the eSIM you just bought — the question that needs a clear answer is which line background traffic leaves through. If the phone is still set to take data from the home SIM, all background work travels over that line in roaming, which has nothing to do with the eSIM's allowance. Conversely, if data is set to the eSIM but you left automatic line switching on, the phone may hop back to the home SIM by itself at certain moments.

The fastest check is three things in the cellular settings screen: which line is set as the data line, whether data roaming on the home line is on or off, and whether a feature allowing automatic data line switching is enabled. The names for those three differ by manufacturer, but the concept is the same on every phone.

Tethering a laptop is background data you cannot see

When you share internet from a phone to a laptop or tablet, the phone's counter only sees that traffic went out; it has no idea what the far end is doing. The trouble is that a laptop has background jobs of its own — syncing files in a cloud folder, updating the operating system, updating installed applications — and those files are usually far larger than anything that happens on a phone.

Before you connect for the first time, mark that connection as metered or limited in the laptop's operating system. The name varies by platform, but the effect is the same: the system defers data-heavy jobs until it finds an unmetered network. It is also worth pausing cloud folder syncing by hand, because some applications ignore the system-level setting.

Switching off per app beats switching off everything

Killing all background activity with one master switch sounds decisive, but the side effect is that you miss things you needed immediately — a message from the person you are meeting, or a gate-change alert. The balanced approach is to go app by app, asking two questions of each: does this app need to update itself while I am not looking at it, and would ten minutes of delay actually cost me anything?

For most apps the answer is no and nothing — shopping apps, news apps, social apps, banking apps you open deliberately anyway. The ones worth leaving alone are usually the chat app you use to reach people on the trip, the airline app, and the maps app that needs to update a route.

Games, music apps and content that downloads as you go

There is another category that is not strictly background but is not something the user asked for either: content an app pulls down while you are using it. Many games fetch extra scenes or audio when you reach a new level, some music apps pre-load the next track in case the signal drops, and video apps routinely buffer minutes ahead so the picture does not stutter. All of it happens quietly while you believe you are simply using the app.

If you intend to use these apps on the trip, load what you need while on Wi-Fi first: playlists, offline maps, podcast episodes, and any game update files. Half an hour of preparation at the hotel helps far more than rationing yourself on the road.

What the symptom you see usually points to

What to do on arrival, before enabling the data line

• Switch off automatic photo backup in whichever gallery or cloud app you use
• Set the app store to download updates only over Wi-Fi
• Turn off auto-download of media in chat apps on the mobile data side only
• Confirm the eSIM is the data line and that data roaming on the home SIM is off
• Reset the data counter so the number you watch belongs to this trip only
• Download offline maps of the city while still on Wi-Fi
• If you plan to tether, mark the connection metered on the receiving device first

Remember to undo the settings when you get home

A lot of people switch everything off before a trip and forget to switch it back. Months later the photos on the phone have never been backed up, apps sit on old versions until some feature stops working, and certain group messages arrive later than they should. Once you are back on unmetered Wi-Fi there is no downside to turning it all on again.

A reliable guard against forgetting is a calendar reminder on your return date that spells out what to switch back on, or a note on the phone listing what you disabled written at the moment you disabled it. It takes seconds and it genuinely works.

Choose a plan size with background data allowed for

When sizing a plan, most people reason from what they intend to do: hours of maps a day, a few photos sent home. They forget the background work that happens daily without asking anyone. If you have measured your own figure using the method above, multiply it by the number of days and add it to the estimate from deliberate use. The result lands much closer to reality.

If you have tuned the settings until background usage is genuinely small, you can comfortably buy a smaller plan. But if you know you would rather not touch settings at all and want to use the phone exactly as you do at home, allowing for more headroom from the outset makes for a smoother trip.

Estimate how much data your trip will need

Browse plans sized for how you actually use data