Where to check your data usage on iPhone
Open Settings, then tap Cellular (or Mobile Data on some regions). Scroll down and you will see Cellular Data with a number showing how much data you have used in the current billing cycle. This is the fastest way to see your total.
The number resets on the date your carrier bills you each month. If you just switched carriers or changed your plan, the reset date may have shifted. Your carrier's own app or website will show the exact date your cycle restarts.
If you want to see which apps are using the most data, stay in the Cellular settings screen and look below the total. Each app is listed with its own data count. Apps that use Wi-Fi only will not appear here — only apps that have used cellular data show up in this list.
Key Takeaways
- Your total cellular data use appears in Settings > Cellular, and it resets each month on your carrier's billing date.
- The same screen shows you which individual apps have used the most data, so you can spot unexpected heavy users.
- Wi-Fi usage does not count toward your cellular data limit and does not appear in the Cellular settings breakdown.
- Turning on Low Data Mode in the same settings screen tells apps to use less data, though not all apps respect this setting.
- Your carrier's app or website usually shows a more detailed breakdown and tells you exactly when your billing cycle resets.
Understanding what counts as cellular data
Cellular data is any information your iPhone sends or receives using your carrier's network — not Wi-Fi. Streaming video, loading web pages, sending messages through apps, downloading files, and checking email all use cellular data if you are not on Wi-Fi.
Background app refresh can use data even when you are not actively using an app. If an app is set to refresh in the background, it may check for new messages, weather updates, or notifications while your phone is in your pocket. You can turn this off per app in Settings > General > Background App Refresh.
Some apps use data in ways you might not expect. Maps can read map tiles in the background. Photos can upload to iCloud. Siri can send voice requests to Apple's servers. None of these show a visible notification that data is being used.
Turning on Low Data Mode to reduce usage
Low Data Mode tells your iPhone and its apps to use less data. Go to Settings > Cellular > Cellular Data Options > Low Data Mode and toggle it on. When it is on, apps will avoid downloading large files, streaming video at lower quality, and refreshing in the background.
Not every app respects Low Data Mode. Apple's own apps (Mail, Maps, Photos, Music) generally do. Third-party apps may ignore it entirely. The only way to know is to turn it on and watch whether the app behaves differently.
You can also turn on Low Data Mode just for Wi-Fi. Go to Settings > Wi-Fi, tap the network you are connected to, and toggle on Low Data Mode for that specific network. This is useful if your home Wi-Fi is slow or has a data cap.
Checking data use by individual app
In Settings > Cellular, scroll past the total and you will see every app listed with its own data count. The apps using the most data appear at the top. If an app shows a number you did not expect, that is a sign it is running in the background or using data in a way you did not notice.
The list does not tell you whether the data was used while you were actively using the app or in the background. To see background usage, go to Settings > General > Background App Refresh and look for apps you do not use often. Turning off background refresh for those apps will cut their data use to zero unless you open them manually.
Some apps let you control their data use directly. Open the app's own settings (not iPhone Settings) and look for options like "stream quality", "auto-play", or "read over Wi-Fi only". These settings override what your iPhone does globally.
Resetting your data counter and tracking across billing cycles
The number in Settings > Cellular resets automatically on your billing date. You cannot manually reset it mid-cycle. If you want to track your own usage between now and your reset date, write down the current number and subtract it from future checks.
Your carrier tracks the same data and usually shows a more detailed view in their app or website. Open your carrier's app (Verizon, AT&T, T-Mobile, etc.) and look for "Data Usage" or "Account". You will see your current cycle, your limit, and sometimes a day-by-day breakdown. This is often more reliable than the iPhone's built-in counter because carriers measure data at their network level.
If your carrier's number and your iPhone's number do not match, the difference is usually small and comes from how each system rounds or counts overhead. A difference of 50 MB to 100 MB is normal. Larger gaps may mean an app is using data in a way the iPhone is not counting, or your carrier is counting overhead the iPhone ignores.
Why your data use might be higher than expected
Background app refresh is the most common culprit. Apps checking for messages, news, or updates while you sleep can add up quickly. Go to Settings > General > Background App Refresh and turn it off for apps you do not need constant updates from.
Video and music streaming use far more data than text. A single hour of video at standard quality uses 0.5 to 1 GB. Music streaming uses roughly 40 to 50 MB per hour. If you stream a lot, switching to Wi-Fi for these activities will cut your data use dramatically.
iCloud backups, photo uploads, and cloud syncing can run in the background. If you have iCloud Photos turned on and your phone is backing up thousands of photos, that can use several hundred MB in a day. Check Settings > [Your Name] > iCloud to see what is syncing and turn off what you do not need.
Location services, weather updates, and map data also use data. Apps like Maps, Weather, and Find My can refresh location data in the background. If you do not use these features, turning them off in Settings > Privacy > Location Services will stop the data use.
Setting up alerts when you approach your limit
Your iPhone does not have a built-in alert for approaching your data limit. Your carrier usually offers this through their app or website. Open your carrier's app and look for "Usage Alerts" or "Data Warnings". Most carriers let you set an alert at 75%, 90%, or a custom amount.
Some carriers also let you set a hard limit that stops data use once you hit it. This prevents overage charges, but it also means your phone will not work on cellular until your next billing cycle. Check your carrier's settings to see if this option is available and whether you want it on.
If your carrier does not offer alerts, you can set a reminder on your calendar to check your usage on a specific day each month. This is less convenient but works if you want to stay aware without relying on your carrier's app.
Frequently Asked Questions
Does Wi-Fi calling use my cellular data?
No. Wi-Fi calling uses your Wi-Fi connection, not your cellular data. When you make a call or send a message over Wi-Fi, it does not count toward your data limit. Your phone will use Wi-Fi calling automatically when your cellular signal is weak and Wi-Fi is available.
Why does my iPhone show more data use than my carrier's app?
Your iPhone counts data from the moment your billing cycle resets. Your carrier counts data at their network level and may have a slight delay in reporting. If the difference is under 100 MB, it is normal. Larger gaps may mean an app is using data in the background without the iPhone counting it properly.
Can I see how much data I used on a specific day?
Your iPhone does not break down data by day. Your carrier's app usually does. Open your carrier's app and look for a daily or weekly breakdown in the usage section. This shows you which days you used the most data and can help you spot patterns.
Does turning off cellular data completely stop all data use?
Yes. If you go to Settings > Cellular and toggle off Cellular Data, your phone will not use any cellular data. It will still use Wi-Fi if you are connected. Emergency calls will still work even with cellular data off.
What happens if I go over my data limit?
That depends on your carrier and plan. Some carriers charge per GB over the limit. Others slow your speed to 2G or 3G until your next billing cycle. A few include unlimited data. Check your carrier's website or call them to know what happens when you exceed your limit.