How to check which apps use the most data on iPhone

No doubt you’ve allowed dozens (or even hundreds) of apps to live on your smartphone, and it’s important to know what those apps are up to. Part of that is tracking how much each application communicates with the outside world. We previously wrote about how to check data usage on an Android device, but here we’ll focus on the iPhone.

There are several reasons to watch how much data your phone is using. First, while unlimited data plans are much more widespread than they used to be, be aware that these plans often apply speed caps once you go over a certain point each month. And if you’re on a limited plan and apps exceed your data allowance while you’re away from Wi-Fi, it could start to cost you, especially if you’re overseas.

Then there’s the privacy aspect: look into your phone’s data usage and you might find that some apps load and download a lot more than they really should given their functionality. It’s another method for spotting suspicious app activity that needs further investigation.

Before digging into these settings, we recommend checking the details of your data plan so you know what your limits are. This is usually done on the web or through an app. You should be able to find this out from your carrier. AT&T, Verizon, and T-Mobile have FAQ pages for help.

To find out how much data your apps have used on iOS, open Settings, then tap Cellular. At the very top, you have a switch to turn cellular data on or off — turn it off and apps won’t be able to connect to the internet at all unless you’re connected to Wi-Fi. (Calls and messages will still work.)

• Touch Mobile data options to turn Data roaming on or off. This affects access to mobile data when you are outside your carrier’s network (usually if you are abroad).
• Back to Cellular screen, scroll down to see how much mobile and roaming data you’ve used in the “current period”—that is, since you last manually reset these stats.
• With each installed application, it is indicated how much data it has uploaded or downloaded in this current period. You’ll notice that the apps that have consumed the most data are listed at the top. Use the switches on the right to block mobile data access for specific apps.
• Touch System services to see data usage for the iOS system, covering activities such as push notifications and software updates.

Scroll all the way down past the app list and you’ll see when your data usage statistics were last cleared. If you want to cancel them (perhaps to track usage for the day or week), tap Reset statistics.

In addition to blocking individual apps from accessing mobile data or turning them off completely, there’s another option on iOS that you can use to limit data usage while you’re not connected to Wi-Fi: Low Data Mode.

Apple says this pauses automatic updates and “background tasks” while you’re not connected to Wi-Fi, though it doesn’t go into too much detail about what those background tasks are. One trade-off that is specifically mentioned is the slower transfer speed on FaceTime calls.

• In iOS settings, tap Cellular and then Mobile data options.
• Touch Data mode find Low data mode option.

The options you see next to Low data mode will vary depending on your network. For example, you might see an option to allow more data on 5G, which means your iPhone will use a faster 5G connection over Wi-Fi, if available.

Don’t forget that there’s always airplane mode if you want to be absolutely sure that apps aren’t transmitting any data over cellular networks or Wi-Fi. A swipe down from the top-right corner of the screen will reveal the Control Center, and you can then tap the airplane icon to enable or disable airplane mode.