What uses your data on android

How to Track Data Usage on Your Android Device

Avoid extra fees and extend your phone’s battery life

What to Know

• Go to Settings >Connections >Data usage >Mobile data usage and tap any app for usage info.
• Tap the toggle at Data usage >Data saver to turn it on.
• Or, try a third-party app, such as one offered by your carrier.

This article demonstrates how to track your data consumption and offers ways to cut down on your data usage without much inconvenience.

Instructions in this article apply to smartphones with Android 10, 9, 8, or 7, with minor variations among manufacturers.

How to Check Data Usage on Android

The instructions below should get you information about your data use.

Open the Settings app.

Tap Connections.

Tap Data usage.

Tap Mobile data usage.

The top of the screen displays your data usage for the current month (as determined by your billing cycle). Tap the date to see previous periods.

Scroll down and tap any app to find out how much data it uses and to control whether it can use mobile data, Wi-Fi, or both.

Go back to Data usage and tap Billing cycle to set the date when your plan resets the monthly billing cycle.

Go to Data usage > Data saver.

Tap the toggle to turn on Data Saver.

Depending on the carrier, phone manufacturer, and Android version, some phones may have additional options for checking data usage.

Third-Party Apps for Tracking Data Usage

There are also third-party apps for monitoring data usage. The four majors carriers offer apps (myAT&T, T-Mobile My Account, Sprint Zone, and My Verizon Mobile) that sync with your account.

Other popular data management apps include My Data Manager and Data Usage. Each app can set up limits and alerts, and My Data Manager tracks data usage in shared or family plans and across multiple devices. Data Usage tracks Wi-Fi usage and predicts when you might go over your data allotment based on daily use. You can set daily, weekly, and monthly data limits too.

Tips for Reducing Data Usage

If your plan has a data limit, upgrading it is not the only way to control overages. Here are a few strategies:

• Most carriers offer shared plans, so team up with your partner, a trusted friend, or family members to save some money.
• Go to the data usage section of the smartphone settings to restrict background data on apps, either one by one or all at once. This way, apps don’t consume data when you’re not using the phone, although it may affect how they work.
• Use Wi-Fi rather than mobile data whenever possible, such as when you’re at home or work.

Beware of unsecured Wi-Fi networks, such as those at coffee shops and other public locations where your privacy could be compromised. If you use public Wi-Fi, consider investing in a hotspot device.

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Data and file storage overview

Android uses a file system that’s similar to disk-based file systems on other platforms. The system provides several options for you to save your app data:

• App-specific storage: Store files that are meant for your app’s use only, either in dedicated directories within an internal storage volume or different dedicated directories within external storage. Use the directories within internal storage to save sensitive information that other apps shouldn’t access.
• Shared storage: Store files that your app intends to share with other apps, including media, documents, and other files.
• Preferences: Store private, primitive data in key-value pairs.
• Databases: Store structured data in a private database using the Room persistence library.

The characteristics of these options are summarized in the following table:

Type of content	Access method	Permissions needed	Can other apps access?	Files removed on app uninstall?
App-specific files	Files meant for your app’s use only	From internal storage, getFilesDir() or getCacheDir() From external storage, getExternalFilesDir() or getExternalCacheDir()	Never needed for internal storage Not needed for external storage when your app is used on devices that run Android 4.4 (API level 19) or higher	No	Yes
Media	Shareable media files (images, audio files, videos)	MediaStore API	READ_EXTERNAL_STORAGE when accessing other apps’ files on Android 11 (API level 30) or higher READ_EXTERNAL_STORAGE or WRITE_EXTERNAL_STORAGE when accessing other apps’ files on Android 10 (API level 29) Permissions are required for all files on Android 9 (API level 28) or lower	Yes, though the other app needs the READ_EXTERNAL_STORAGE permission	No
Documents and other files	Other types of shareable content, including downloaded files	Storage Access Framework	None	Yes, through the system file picker	No
App preferences	Key-value pairs	Jetpack Preferences library	None	No	Yes
Database	Structured data	Room persistence library	None	No	Yes

The solution you choose depends on your specific needs:

How much space does your data require? Internal storage has limited space for app-specific data. Use other types of storage if you need to save a substantial amount of data. How reliable does data access need to be? If your app’s basic functionality requires certain data, such as when your app is starting up, place the data within internal storage directory or a database. App-specific files that are stored in external storage aren’t always accessible because some devices allow users to remove a physical device that corresponds to external storage. What kind of data do you need to store? If you have data that’s only meaningful for your app, use app-specific storage. For shareable media content, use shared storage so that other apps can access the content. For structured data, use either preferences (for key-value data) or a database (for data that contains more than 2 columns). Should the data be private to your app? When storing sensitive data—data that shouldn’t be accessible from any other app—use internal storage, preferences, or a database. Internal storage has the added benefit of the data being hidden from users.

Categories of storage locations

Android provides two types of physical storage locations: internal storage and external storage. On most devices, internal storage is smaller than external storage. However, internal storage is always available on all devices, making it a more reliable place to put data on which your app depends.

Removable volumes, such as an SD card, appear in the file system as part of external storage. Android represents these devices using a path, such as /sdcard .

Apps themselves are stored within internal storage by default. If your APK size is very large, however, you can indicate a preference within your app’s manifest file to install your app on external storage instead:

Permissions and access to external storage

On earlier versions of Android, apps needed to declare the READ_EXTERNAL_STORAGE permission to access any file outside the app-specific directories on external storage. Also, apps needed to declare the WRITE_EXTERNAL_STORAGE permission to write to any file outside the app-specific directory.

More recent versions of Android rely more on a file’s purpose than its location for determining an app’s ability to access, and write to, a given file. In particular, if your app targets Android 11 (API level 30) or higher, the WRITE_EXTERNAL_STORAGE permission doesn’t have any effect on your app’s access to storage. This purpose-based storage model improves user privacy because apps are given access only to the areas of the device’s file system that they actually use.

Android 11 introduces the MANAGE_EXTERNAL_STORAGE permission, which provides write access to files outside the app-specific directory and MediaStore . To learn more about this permission, and why most apps don’t need to declare it to fulfill their use cases, see the guide on how to manage all files on a storage device.

Scoped storage

To give users more control over their files and to limit file clutter, apps that target Android 10 (API level 29) and higher are given scoped access into external storage, or scoped storage, by default. Such apps have access only to the app-specific directory on external storage, as well as specific types of media that the app has created.

Use scoped storage unless your app needs access to a file that’s stored outside of an app-specific directory and outside of a directory that the MediaStore APIs can access. If you store app-specific files on external storage, you can make it easier to adopt scoped storage by placing these files in an app-specific directory on external storage. That way, your app maintains access to these files when scoped storage is enabled.

To prepare your app for scoped storage, view the storage use cases and best practices guide. If your app has another use case that isn’t covered by scoped storage, file a feature request. You can temporarily opt-out of using scoped storage.

View files on a device

To view the files stored on a device, use Android Studio’s Device File Explorer.

Additional resources

For more information about data storage, consult the following resources.

Videos

Content and code samples on this page are subject to the licenses described in the Content License. Java is a registered trademark of Oracle and/or its affiliates.

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Data encryption on Android with Jetpack Security

Update: April 21st, 2021: Jetpack Security is now stable 1.0.0!
Update: December 2nd, 2021: Jetpack Security 1.1.0–Alpha-03 released, adding support for API level 21+ which includes a redesigned MasterKey implementation.

Have you ever tried to encrypt data in your app? As a developer, you want to keep data safe, and in the hands of the party intended to use. But if you’re like most Android developers, you don’t have a dedicated security team to help encrypt your app’s data properly. By searching the web to learn how to encrypt data, you might get answers that are several years out of date and provide incorrect examples.

The Jetpack Security (JetSec) crypto library provides abstractions for encrypting Files and SharedPreferences objects. The library promotes the use of the AndroidKeyStore while using safe and well-known cryptographic primitives. Using EncryptedFile and EncryptedSharedPreferences allows you to locally protect files that may contain sensitive data, API keys, OAuth tokens, and other types of secrets.

Why would you want to encrypt data in your app? Doesn’t Android, since 5.0, encrypt the contents of the user’s data partition by default? It certainly does, but there are some use cases where you may want an extra level of protection. If your app uses shared storage, you should encrypt the data. In the app home directory, your app should encrypt data if your app handles sensitive information including but not limited to personally identifiable information (PII), health records, financial details, or enterprise data. When possible, we recommend that you tie this information to biometrics for an extra level of protection.

Jetpack Security is based on Tink, an open-source, cross-platform security project from Google. Tink might be appropriate if you need general encryption, hybrid encryption, or something similar. Jetpack Security data structures are fully compatible with Tink.

Key Generation

Before we jump into encrypting your data, it’s important to understand how your encryption keys will be kept safe. Jetpack Security uses a master key, which encrypts all subkeys that are used for each cryptographic operation. JetSec provides a recommended default master key in the MasterKeys class. This class uses a basic AES256-GCM key which is generated and stored in the AndroidKeyStore. The AndroidKeyStore is a container which stores cryptographic keys in the TEE or StrongBox, making them hard to extract. Subkeys are stored in a configurable SharedPreferences object.

Primarily, we use the AES256_GCM_SPEC specification in Jetpack Security, which is recommended for general use cases. AES256-GCM is symmetric and generally fast on modern devices.

For apps that require more configuration, or handle very sensitive data, it’s recommended to build your KeyGenParameterSpec , choosing options that make sense for your use. Time-bound keys with BiometricPrompt can provide an extra level of protection against rooted or compromised devices.

• userAuthenticationRequired() and userAuthenticationValiditySeconds() can be used to create a time-bound key. Time-bound keys require authorization using BiometricPrompt for both encryption and decryption of symmetric keys.
• unlockedDeviceRequired() sets a flag that helps ensure key access cannot happen if the device is not unlocked. This flag is available on Android Pie and higher.
• Use setIsStrongBoxBacked() , to run crypto operations on a stronger separate chip. This has a slight performance impact, but is more secure. It’s available on some devices that run Android Pie or higher.

Note: If your app needs to encrypt data in the background, you should not use time-bound keys or require that the device is unlocked, as you will not be able to accomplish this without a user present.

Unlocking time-bound keys

You must use BiometricPrompt to authorize the device if your key was created with the following options:

• userAuthenticationRequired is true
• userAuthenticationValiditySeconds > 0

After the user authenticates, the keys are unlocked for the amount of time set in the validity seconds field. The AndroidKeystore does not have an API to query key settings, so your app must keep track of these settings. You should build your BiometricPrompt instance in the onCreate() method of the activity where you present the dialog to the user.

BiometricPrompt code to unlock time-bound keys

Encrypt Files

Jetpack Security includes an EncryptedFile class, which removes the challenges of encrypting file data. Similar to File , EncryptedFile provides a FileInputStream object for reading and a FileOutputStream object for writing. Files are encrypted using Streaming AEAD, which follows the OAE2 definition. The data is divided into chunks and encrypted using AES256-GCM in such a way that it’s not possible to reorder.

Encrypt SharedPreferences

If your application needs to save Key-value pairs — such as API keys — JetSec provides the EncryptedSharedPreferences class, which uses the same SharedPreferences interface that you’re used to.

Both keys and values are encrypted. Keys are encrypted using AES256-SIV-CMAC, which provides a deterministic cipher text; values are encrypted with AES256-GCM and are bound to the encrypted key. This scheme allows the key data to be encrypted safely, while still allowing lookups.

More Resources

FileLocker is a sample app on the Android Security GitHub samples page. It’s a great example of how to use File encryption using Jetpack Security.

For the latest developments, please check back here. For questions, feel free to reach out to me (@jonmarkoff) on Twitter.

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