Where to find your data usage on iPhone
Open Settings, tap Cellular, and scroll down to see your total data usage since your last reset. The number next to "Cellular Data" shows how much data your phone has used on your carrier's network. Below that, you'll see a list of every app installed on your phone, ranked by how much data each one has consumed.
The same information appears under Settings > Mobile Data if you're outside the United States. The layout and app list are identical — Apple just uses different terminology in different regions.
These numbers reset automatically on the date your phone bill renews each month. You can change that reset date by going to Settings > Cellular > Cellular Plans (or Mobile Plans), selecting your plan, and tapping "Billing Cycle". If you have multiple phone plans on one device, each plan shows its own separate data counter.
Key Takeaways
- Your total data usage appears in Settings > Cellular, and resets automatically on your monthly billing date.
- Each app's data consumption is listed below your total, so you can see which apps are using the most.
- Wi-Fi usage does not count toward your cellular data limit and appears in a separate section.
- Turning off Background App Refresh and disabling automatic updates over cellular are the fastest ways to reduce data use.
- You can set a data warning or limit in Settings > Cellular > Cellular Data Limit to get alerts before you run out.
The difference between Wi-Fi and cellular data
Your iPhone tracks Wi-Fi usage separately from cellular data. Wi-Fi does not count toward your monthly data limit with your phone carrier, so you can use as much as you want without affecting your bill. To see Wi-Fi usage, go to Settings > Wi-Fi and tap the information icon next to your connected network.
When your phone is connected to Wi-Fi, apps will use that connection instead of cellular data whenever possible. If you turn off Wi-Fi or move out of range, your phone automatically switches to cellular. Some apps let you choose which connection type to use — for example, you can set YouTube to play video only over Wi-Fi to save cellular data.
If you're trying to reduce your cellular bill, focus on the apps using the most data in the cellular list. Apps that show high numbers in the Wi-Fi section are not costing you anything extra.
Which apps use the most data and why
Video streaming apps like YouTube, TikTok, and Netflix almost always rank at the top of the data usage list because video files are large. A single hour of video can use 500 megabytes to 3 gigabytes depending on the quality setting. Social media apps like Instagram and Facebook use significant data because they automatically load images and video in your feed.
Maps and navigation apps use data whenever they read map tiles or fetch real-time traffic information. Music streaming apps like Spotify and Apple Music use less data than video but add up quickly if you listen for hours every day. Email and messaging apps use very little data unless you're sending large attachments or photos.
If an app shows high data usage but you barely use it, it may be downloading content in the background. Podcasts, news apps, and music apps often read new episodes or articles automatically. You can turn this off in the app's settings or by disabling Background App Refresh for that specific app in Settings > General > Background App Refresh.
Setting a data warning or limit
Go to Settings > Cellular > Cellular Data Limit and toggle on "Set Limit". Choose the amount of data you want to allow each month — this should match your phone plan's limit. Your phone will warn you when you reach 80 percent of that limit and will stop using cellular data entirely once you hit 100 percent.
When your limit is reached, you can still make calls and send texts, but apps cannot use cellular data until your billing cycle resets. This prevents surprise overage charges if your carrier charges extra for data beyond your plan. You can temporarily turn off Data Saver mode to allow data again, but your phone will remind you that you've exceeded your limit.
If you have a plan with a very small data limit, turning on Low Data Mode in Settings > Cellular > Cellular Data Options will reduce how much data apps use. This disables automatic video playback, lowers image quality, and prevents background downloads. Low Data Mode only affects cellular — Wi-Fi usage is not restricted.
Reducing data usage without changing your plan
Turn off Background App Refresh for apps you don't need to update constantly. Go to Settings > General > Background App Refresh, tap the toggle next to each app, and choose "Wi-Fi" or "Off". This stops apps from checking for new messages, emails, or content when you're not actively using them on cellular.
Disable automatic app updates over cellular by going to Settings > App Store > App Updates and turning off the toggle. Your apps will still update automatically over Wi-Fi, but not when you're on cellular. This prevents large app updates from eating into your monthly limit without your knowledge.
In Settings > Photos, turn off "iCloud Photos" if you have it enabled, or set it to "read and Keep Originals" instead of "Optimize iPhone Storage". The optimization setting uploads full-resolution photos to iCloud, which uses data every time you take a picture. You can also disable automatic iCloud backups over cellular in Settings > [Your Name] > iCloud > iCloud Backup.
Understanding data usage spikes
If your data usage suddenly jumps without explanation, check the app list in Settings > Cellular to see which app caused it. Sometimes a single app update, a large email attachment, or a video that auto-played in your feed can account for hundreds of megabytes. Scrolling through your app list from highest to lowest data use usually reveals the culprit within seconds.
If an app shows data usage but you haven't used it recently, it may be downloading content in the background. Podcast apps read new episodes, news apps fetch articles, and music apps cache songs for offline listening. Check the app's settings to see if automatic downloads are enabled, and turn them off if you want to control when large files are downloaded.
Resetting your data counter does not delete any data from your phone — it only resets the counter that tracks usage. Go to Settings > Cellular > Reset Statistics to start fresh. This is useful if you want to measure data usage for a specific time period that doesn't match your billing cycle.
Checking data usage on a family plan
If you're on a family plan, each person's iPhone tracks their own data usage separately. Open Settings > Cellular on each phone to see that person's individual usage. The family plan holder can see everyone's usage in the carrier's app or website, but the iPhone settings app only shows each person their own number.
Some carriers let you set individual data limits for each family member through their app. This works the same way as a personal limit — the phone warns when 80 percent is reached and stops using cellular data at 100 percent. Check your carrier's app to see if this option is available for your plan.
Frequently Asked Questions
Why does my data usage keep resetting?
Your data counter resets automatically on your billing cycle date, which your carrier sets. You can change when this happens by going to Settings > Cellular > Cellular Plans, selecting your plan, and tapping "Billing Cycle". If you see the counter reset on unexpected dates, check that your billing cycle date matches when your phone bill is due.
Does using FaceTime or iMessage count toward my data limit?
FaceTime and iMessage use data when you're on cellular, and that data counts toward your limit. However, both apps use very little data compared to video streaming or social media. If you're on a tight data budget, using Wi-Fi for FaceTime calls will save the most data.
Can I see data usage for a specific date or week?
The iPhone settings app only shows total usage since your last reset. To track usage by date, you can take a screenshot of your data usage each day, or check your carrier's app or website — most carriers show daily or weekly breakdowns. Some third-party apps also track data usage by date, though they require permission to monitor your network activity.
What does "System Data" mean in my usage list?
System Data is data used by iOS itself for updates, iCloud syncing, and other background processes that aren't tied to a specific app. It's usually a small percentage of your total usage. If System Data is unusually high, check Settings > General > iPhone Storage to see if a large iOS update is pending.
Why is my data usage so high even though I use Wi-Fi most of the time?
Check the app list in Settings > Cellular to find which app is using the most data. If a video app is at the top, it may have played videos over cellular when you weren't paying attention. If a social media app is high, try disabling autoplay in that app's settings. You can also turn on Low Data Mode to reduce background data use.