How to Easily Check Your iPhone Data Usage

This article explains how to check your iPhone data usage and avoid overages or speed reductions. Instructions in this article apply to iOS 9 and later.

How to Check Your Data Usage Through Your Carrier

Most carriers include a tool—either a mobile app or your online account portal—to show your usage in the current billing period.

Also, several carriers offer a device-specific code that displays your data usage to date, through your device's Phone app or the dialer:

• AT&T: Call #DATA# to receive a text message with your current usage.
• Sprint: Call *4 and follow the menus.
• Straight Talk: Text usage to 611611 to receive a reply with your current use.
• T-Mobile: Call #932#.
• Verizon: Call #data.

How to Check Data Use on Your Phone

Your iPhone offers a built-in tool to track your data usage, but it has limitations. To find the tool, open the Settings app and tap Cellular. The screen reveals your current usage relative to your allotment.

Different vendors interact with this app in different ways. For example, T-Mobile syncs billing periods, so the usage rates should more-or-less match. Other vendors may not sync—thus, the current period noted in the app may not match the billing cycle.

How to Save Data When You're Close to Your Limit​

Most carriers send a warning when you near your data limit. Try one or more of several strategies to reduce your cellular data usage:

• Disable cellular data by app: The iPhone controls which apps can use data and which only work when the phone is connected to Wi-Fi. Disable data-hogging apps by going to Settings > Cellular and in the Cellular Data section, move the toggle switch to off/white for apps to restrict.
• Disable all cellular data:​ You can also disable all cellular data while keeping your ability to use the phone and send and receive texts.​ Go to Settings > Cellular and​ move the Cellular Data toggle switch to off/white.
• Disable Wi-Fi Assist: This feature of iOS 9 and up automatically switches to cellular data when Wi-Fi isn't working well. It's a nice feature, but it also uses data. Turn it off in Settings > Cellular. Scroll to the bottom and move the Wi-Fi Assist toggle switch to off/white.
• Disable Automatic Downloads: If you own several iOS devices, you may have set up to automatically download new apps and media on all devices when you download those to one. It's great to keep your devices in sync, but it can eat up cellular data. Restrict these downloads to Wi-Fi in Settings > iTunes & App Store. Move the Use Cellular Data toggle switch to off/white. 
• Limit Background App Refresh to Wi-Fi: Background App Refresh updates apps even when you're not using them so they have the latest data the next time you open them. Force these updates to only occur over Wi-Fi by going to Settings > General > Background App Refresh.