The biggest battery drains on your iPhone

Your iPhone battery drains fastest when the screen is on at high brightness, when apps run location services in the background, when your phone searches for a weak cellular signal, and when Bluetooth or Wi-Fi stays active but disconnected. These four things account for most unexpected battery loss. The screen alone can use 30 to 40 percent of your battery in a day of normal use.

Beyond those, background app refresh — the feature that lets apps update their content when you are not looking — drains power constantly. Push notifications force your phone to wake and light the screen. Video streaming and gaming drain the battery faster than any other activity because they demand the processor, graphics chip, and screen all at once.

Less obvious drains include location services running for maps or weather apps, automatic downloads of photos and videos over cellular, and keeping your phone in a cold environment, which makes the battery chemistry work harder. If your battery drops 10 to 15 percent in an hour of light use, one of these is almost certainly the culprit.

Key Takeaways

  • Screen brightness and screen-on time are responsible for the largest share of battery drain on most iPhones.
  • Background app refresh, location services, and push notifications drain battery even when you are not actively using the phone.
  • Cellular signal searching, Bluetooth searching, and Wi-Fi staying active without a connection all consume power continuously.
  • Video streaming, gaming, and photo syncing over cellular drain battery much faster than browsing or messaging.
  • You can see which apps are draining the most battery by opening Settings, Battery, and Battery Usage.

How to check which apps are using the most battery

Open Settings on your iPhone, then tap Battery. You will see a percentage showing how much battery you have used in the last 24 hours or the last 10 days — tap the time period you want to check. Below that, tap Battery Usage to see a list of every app and how much battery each one consumed.

The list shows apps in order from highest to lowest drain. If an app is using more than 10 percent of your battery and you barely use it, that app is the problem. Tap any app name to see whether it used battery while the screen was on or in the background. If a messaging app or social media app is draining 20 percent of your battery, background app refresh is almost certainly running for that app even when you closed it.

iOS also shows you the percentage of battery used while the screen was on versus off. An app that uses most of its battery with the screen off is running in the background. An app that uses most of its battery with the screen on is straightforward demanding — you are using it, and it is hungry for power.

Screen brightness and display settings that save the most battery

Lowering your screen brightness to 30 to 40 percent for indoor use can extend your battery by two to four hours per day. If you find manual brightness adjustment annoying, turn on Auto-Brightness in Settings, Display & Brightness. Your phone will dim the screen in dim rooms and brighten it in sunlight, which keeps the screen efficient without you having to think about it.

Switching to Dark Mode also saves battery on iPhones with OLED screens — the iPhone 12 and newer. Dark Mode makes the screen display black pixels by turning them off completely, which uses less power than displaying white or bright colors. On older iPhones with LCD screens, Dark Mode makes almost no difference to battery life.

If you want the most aggressive battery saving, turn on Low Power Mode in Settings, Battery. This disables background app refresh, reduces animation, lowers performance, and dims the screen. Most people can use their phone normally in Low Power Mode and gain 10 to 20 percent more battery life. You can turn it on at any battery percentage, not just when you are low.

Background app refresh and location services

Background app refresh lets apps update their content even when you are not using them — so your email app can fetch new messages, your weather app can update the forecast, and your news app can load stories. This happens constantly and drains battery. You can turn it off entirely in Settings, General, Background App Refresh, or turn it off for individual apps by tapping each one.

Location services use GPS, which is one of the most power-hungry features on your phone. Many apps request location permission and then track your location in the background even though you do not need that feature. Open Settings, Privacy & Security, Location Services. You will see a list of every app that has location permission. Tap each app and change the setting from "Always" to "While Using" or "Never." Most apps do not need your location when they are closed.

Maps, weather, and fitness apps genuinely need location to work. Social media, messaging, and news apps almost never do. Changing location from "Always" to "While Using" for just three apps can save 5 to 10 percent of your daily battery.

Cellular signal, Bluetooth, and Wi-Fi searching

When your phone cannot find a strong cellular signal, it searches constantly for a better one. This searching drains battery faster than normal use. If you are in a building with weak signal or in a rural area, your phone is working hard to stay connected. The same thing happens with Bluetooth — if your phone is paired to a device that is out of range, it keeps searching for that device.

Turning off Bluetooth when you are not using it saves a small amount of battery. Turning off Wi-Fi when you are not connected to a network saves more, because your phone stops searching for networks. However, if you are on cellular data, leaving Wi-Fi on and letting your phone connect to a known network actually saves battery, because Wi-Fi uses less power than cellular data once connected.

If you are in an area with very weak signal, turning on Airplane Mode and then turning Wi-Fi back on will stop your phone from searching for cellular signal while still letting you use Wi-Fi. This can extend battery life by several hours in a weak-signal area.

Video, gaming, and photo syncing

Streaming video on YouTube, Netflix, or TikTok drains battery faster than almost any other activity because the screen stays on at full brightness, the processor works constantly to decode video, and the network radio stays active. One hour of video streaming can use 15 to 25 percent of your battery. Gaming is similar — the graphics chip and processor both work at maximum, and the screen stays on.

Photo and video syncing over cellular also drains battery quickly. If you have iCloud Photos turned on and your phone is syncing a large photo library over cellular data, that process runs in the background and uses power constantly. Open Settings, Photos, and turn off iCloud Photos if you do not need automatic backup, or make sure it only syncs over Wi-Fi by opening Settings, Photos, and checking the sync settings.

If you use your phone for video calls, expect significant battery drain. A one-hour video call can use 20 to 30 percent of your battery because the camera, microphone, screen, and network radio all run continuously. Plugging in a charger during long calls is the only practical solution.

Temperature and battery health

iPhones perform worst in cold environments. If your phone is below 50 degrees Fahrenheit, the battery chemistry slows down and the phone drains faster or shuts down even though the battery is not actually empty. Warming the phone in your pocket or indoors will restore normal function. Extreme heat also damages battery health over time, so avoid leaving your phone in direct sunlight or in a hot car.

Over time, every iPhone battery degrades. You can check your battery health by opening Settings, Battery, Battery Health & Charging. The number shown is the maximum charge your battery can hold compared to when it was new. A battery at 80 percent health is still usable, but it will not last as long per charge. At 50 percent health, you should consider a battery replacement.

If your battery health is above 80 percent but your phone is draining much faster than it used to, the problem is not the battery itself — it is one of the apps or settings listed above. Check Battery Usage first.

Frequently Asked Questions

Why does my iPhone battery drain so fast overnight?

Background app refresh, push notifications, and location services all run while your phone is locked. If your battery drops more than 5 percent overnight, turn off background app refresh in Settings, General, Background App Refresh, or disable it for individual apps. Also check which apps have permission to send notifications in Settings, Notifications.

Does turning off Wi-Fi save battery?

Only if you are not connected to a network. Once your phone connects to Wi-Fi, leaving it on uses less battery than using cellular data. If your phone is searching for Wi-Fi networks but not connected, turning Wi-Fi off saves a small amount of battery. The bigger savings come from turning off location services and background app refresh.

Can a bad battery be the problem if my phone drains fast?

Check your battery health first in Settings, Battery, Battery Health & Charging. If it is above 80 percent, your battery is fine and the drain is caused by apps or settings. If it is below 50 percent, the battery itself is degraded and a replacement will improve battery life. Most fast drain is caused by apps, not battery age.

Does Low Power Mode slow down my iPhone?

Yes, it reduces performance and disables some features like background app refresh and automatic downloads. However, most people do not notice the slowdown during normal use like messaging, browsing, or email. Gaming and video editing will feel slower. You can turn Low Power Mode on and off anytime without harming your phone.

Why does my phone drain faster in certain locations?

Weak cellular signal causes your phone to search constantly for a stronger connection, which drains battery much faster. If you are in a building with poor signal or a rural area, your phone is working harder to stay connected. Switching to Airplane Mode and using Wi-Fi only, or straightforward accepting the faster drain, are your only options.