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Information About iPhone Performance and Its Relationship with Battery Health

The iPhone is designed to deliver a simple and seamless user experience. This is made possible through a combination of advanced technologies and sophisticated engineering. One area where this is especially evident is in battery and performance. Batteries use complex technology, and there are several variables that affect battery performance and the related performance of the iPhone. All rechargeable batteries are consumable components with a limited lifespan — eventually, their capacity and performance diminish, and they must be recycled. As batteries age, changes in iPhone performance may occur. We’ve compiled this informational material for users who want to learn more.

About Lithium-Ion Batteries
iPhone batteries use lithium-ion technology. Compared to older battery generations, lithium-ion batteries charge faster, last longer, and offer a higher power density for increased battery life in a lighter package. Rechargeable lithium-ion technology currently offers the best performance for your device. Learn more about lithium-ion batteries.

Maximizing Battery Performance
“Battery life” refers to how long a device operates before it needs to be recharged.
“Battery lifespan” refers to how long a battery lasts before it needs to be replaced.

Both are influenced by how you use your device. No matter how you use it, there are ways to extend both. Battery lifespan is tied to its chemical age, which is affected by more than just time — including the number of charge cycles and how the battery has been cared for. Follow these tips to maximize battery performance and extend lifespan. For example, when storing an iPhone long-term, keep the battery around 50% charged. Avoid charging or leaving the device in high-temperature environments (e.g. direct sunlight) for extended periods.

Battery Chemical Aging
All rechargeable batteries are consumable and lose effectiveness due to chemical aging.
As lithium-ion batteries age chemically, the amount of charge they can hold decreases, leading to more frequent recharging. This is referred to as maximum battery capacity, which compares current capacity to what it was when new.

Additionally, the battery’s ability to deliver peak performance may decline. iPhone electronics require instant power from the battery to function properly. One factor that affects this is the battery’s internal resistance — which can increase with chemical aging, especially under low charge or cold temperatures. When this happens, the battery may not be able to supply the required voltage, leading to unexpected shutdowns to protect internal components.

Preventing Unexpected Shutdowns
Unexpected shutdowns are more likely to occur with low battery charge, high chemical age, or colder environments. In extreme cases, this may happen more often, affecting reliability or usability.

For iPhone 6, 6 Plus, 6s, 6s Plus, SE (1st gen), 7, and 7 Plus, iOS dynamically manages peak performance to prevent unexpected shutdowns. This performance management feature is specific to iPhone and is not used in other Apple products. It was introduced in iOS 12.1 for iPhone 8, 8 Plus, and X, and in iOS 13.1 for iPhone XS, XS Max, and XR. These newer models may show fewer effects due to more advanced hardware and software design.

The feature takes into account device temperature, battery charge level, and battery impedance. If needed, iOS will manage performance dynamically across components like the CPU and GPU to prevent shutdown. This balances system tasks and avoids sudden performance spikes. In many cases, the user might not notice any difference.

In extreme cases, you may observe:

Longer app launch times

Lower frame rates during scrolling

Dimming of the backlight (adjustable via Control Center)

Lower speaker volume (up to -3 dB)

Frame rate reduction in some apps

Camera flash being disabled in the UI

Apps requiring a reload when reopening

Unchanged features include:

Cellular call quality and network performance

Recorded photo and video quality

GPS performance

Location accuracy

Sensors (gyroscope, accelerometer, barometer)

Apple Pay functionality

Performance management effects are temporary in cases of low charge or cold weather. However, if the battery has advanced chemical aging, effects may last longer. All rechargeable batteries eventually wear out and must be replaced to restore full performance.

For iOS 11.3 and Later
Starting with iOS 11.3, Apple improved performance management by evaluating the need for it more frequently. If battery health can meet the power demands, management is reduced. If another unexpected shutdown occurs, it is re-applied. This continuous assessment provides more adaptive performance handling.

iPhone 8 and newer models use advanced hardware and software design that enables more accurate estimation of power needs and battery capability, allowing for more refined performance optimization. As all rechargeable batteries age, they lose capacity and maximum performance, and will eventually require replacement.

Learn how to set up your iPhone, iPad, or iPod touch.

IF YOU’RE SWITCHING TO A NEW DEVICE

If you want to transfer your information from another device to your new iPhone, iPad, or iPod touch, follow these steps:

From another iPhone, iPad, or iPod touch

From an Android device

Make sure you’ve backed up your previous iOS device so you can transfer the content to your new device.

IF YOU’RE SETTING UP YOUR FIRST IOS DEVICE

If you’ve already set up your new device but want to start over, learn how to erase your iPhone, iPad, or iPod touch.

Otherwise, follow these steps:

TURN ON YOUR DEVICE

Press and hold the power button until the Apple logo appears. You’ll then see a “Hello” message in many languages. Follow the steps to get started. If you’re visually impaired, you can enable VoiceOver or Zoom from the Hello screen.

When prompted, select your language. Then select your country or region. This affects how information appears on your device, such as the date, time, and contacts. At this point, you can tap the blue accessibility button to configure Accessibility Options to enhance your setup and usage experience.

Get help if your device doesn’t turn on, is disabled, or requires a passcode.

IF YOU HAVE ANOTHER DEVICE WITH IOS 11 OR LATER, USE QUICK START

If you have another device running iOS 11 or later, you can use it to automatically set up your new device with Quick Start. Bring the two devices close together and follow the instructions.

If you don’t have another device with iOS 11 or later, tap “Set Up Manually” to continue.

ACTIVATE YOUR DEVICE

You need to connect to a Wi-Fi network, a mobile network, or iTunes to activate your device and continue setup.

Tap the Wi-Fi network you want to use or choose another option. If you’re setting up an iPhone or iPad (Wi-Fi + Cellular), you might need to insert your SIM card first.

Get help if you can’t connect to Wi-Fi or activate your iPhone.

SET UP FACE ID OR TOUCH ID AND CREATE A PASSCODE

On some devices, you can set up Face ID or Touch ID. These features let you use facial recognition or your fingerprint to unlock your device and make purchases. Tap “Continue” and follow the instructions or tap “Set Up Later in Settings.”

Next, set a six-digit passcode to protect your data. A passcode is required for features like Face ID, Touch ID, and Apple Pay. If you prefer a four-digit code, custom code, or no code, tap “Passcode Options.”

RESTORE OR TRANSFER YOUR INFORMATION AND DATA

If you have an iCloud or iTunes backup or an Android device, you can restore or transfer your data from your old device to the new one.

If you don’t have a backup or another device, select “Don’t Transfer Apps & Data.”

SIGN IN WITH YOUR APPLE ID

Enter your Apple ID and password or tap “Forgot password or don’t have an Apple ID?” From here, you can recover your Apple ID, reset your password, create an Apple ID, or set it up later. If you use multiple Apple IDs, tap “Use different Apple IDs for iCloud and iTunes?”

You may be asked to enter a verification code from your previous device when signing in.

ENABLE AUTOMATIC UPDATES AND SET UP OTHER FEATURES

On the following screens, you can choose whether to share information with app developers and allow iOS to update automatically.

SET UP SIRI AND OTHER SERVICES

You’ll then be prompted to set up or enable services and features like Siri. On some devices, you’ll be asked to say a few phrases so Siri can recognize your voice.

If you’re signed in with your Apple ID, follow the steps to set up Apple Pay and iCloud Keychain.

CONFIGURE SCREEN TIME AND DISPLAY SETTINGS

Screen Time gives you insight into how much time you and your children spend on your devices. You can also set daily limits for app usage. After setting up Screen Time, you can enable True Tone (if supported) and use Display Zoom to adjust icon and text size on the Home screen.

If you have an iPhone X or later, learn how to use gestures to navigate the device. If you have an iPhone 7, 7 Plus, 8, or 8 Plus, you can customize the Home button’s click feel.

FINISH

Tap “Get Started” to begin using your device. Back up your data securely and explore more features in the user guide for iPhone, iPad, or iPod touch.

USE 5G WITH YOUR IPHONE
iPhone 12, iPhone 12 mini, iPhone 12 Pro, and iPhone 12 Pro Max support 5G networks from certain mobile carriers. Learn how to use 5G cellular service on your device.

WHAT YOU NEED
An iPhone 12, iPhone 12 mini, iPhone 12 Pro, or iPhone 12 Pro Max
A mobile carrier that supports 5G
A 5G cellular plan¹
If your new iPhone came with a SIM card, use that SIM. Otherwise, insert the SIM card from your previous iPhone. In some cases, you may need to contact your carrier to set up your old SIM for 5G access.

UNDERSTANDING 5G STATUS BAR ICONS
When you’re in an area with 5G coverage and your 5G plan is active, one of the following icons may appear on your iPhone’s status bar:

5G: Standard 5G network access is available and your iPhone is connected. Not available in all areas.
5G+: Indicates access to higher-frequency 5G from your carrier or active connection to it. Not available in all areas.
5G UW: (Ultra Wideband) Similar to 5G+, indicating high-frequency 5G access or active connection. Not available in all areas.²

Learn what to do if 5G doesn’t appear in your status bar.

LEARN ABOUT 5G SETTINGS
iPhone’s default 5G settings are optimized for battery life and data usage based on your data plan. You can customize these options to control when your iPhone uses 5G and how much data is used by apps.

Go to Settings > Cellular > Cellular Data Options. If you’re using Dual SIM, select the line you want to modify first.

Voice & Data
Choose how your iPhone uses the 5G network, which can affect battery life:
5G Auto: Enables Smart Data mode. Switches to LTE when 5G doesn’t offer noticeable improvement, saving battery.
5G On: Always uses 5G when available, which may reduce battery life.
LTE: Only uses LTE, even when 5G is available.

In mainland China, you can turn Standalone 5G on or off via Settings > Cellular > Cellular Data Options > Voice & Data. This is enabled by default on iOS 14.5 and later for China. With Standalone 5G, all mobile activity uses 5G. Contact your carrier for more details.

Data Mode
Allow More Data on 5G: Enables higher data usage for system tasks and apps, such as high-quality FaceTime, Apple TV+ streaming, Apple Music, and iOS updates. This setting may be default with unlimited data plans.
Standard: Allows automatic updates and background tasks, uses standard video and FaceTime quality.
Low Data Mode: Reduces Wi-Fi and cellular data usage by pausing updates and background activity.

Data Roaming
Many global carriers support 5G roaming. If your carrier doesn’t, you can still access data using 4G/LTE or get a local SIM or eSIM with 5G where available.

Contact your carrier for more information.

IF 5G IS NOT SHOWING IN THE STATUS BAR
Ensure you’re in a 5G coverage area. If unsure, contact your carrier.
Go to Settings > Cellular > Cellular Data Options. If this menu appears, 5G is enabled. If not, check with your carrier to confirm 5G support on your plan.

Toggle Airplane Mode on and off.
If 5G service is still unavailable, contact your carrier.

LEARN MORE
To use 5G with Dual SIM on iPhone 12 models, make sure you have iOS 14.5 or later.
You can stream content at the highest quality by going to Settings > Music > Cellular Data and enabling High Quality Streaming, and also Settings > TV > Cellular > High Quality. These settings use more data and may delay playback start times.
If you enable Low Power Mode, 5G is disabled (except during video streaming). It also disables Standalone 5G where applicable.

¹ Contact your carrier to confirm 5G plan availability. Some carriers may charge an activation fee.
² High-frequency 5G networks (mmWave) are only supported in the U.S. with iPhones purchased in the U.S.

With widgets, you get timely information from your favorite apps at a glance.

In iOS 14, you can use widgets on the Home Screen to access your favorite information instantly. Alternatively, you can use widgets from the Today View by swiping right from the Home Screen or Lock Screen.

Add a widget to your Home Screen

• On the Home Screen, touch and hold a widget or an empty area until the apps jiggle.
• Tap the “Add” button in the upper-left corner.
• Select a widget, choose from three widget sizes, then tap “Add Widget.”
• Tap “Done.”

Add a widget from Today View

• In Today View, touch and hold a widget until the quick action menu appears, then tap “Edit Home Screen.”
• Drag the widget to the right edge of the screen until it appears on the Home Screen.
• Tap “Done.”

Edit a widget

• Touch and hold a widget to open the quick action menu.
• Tap “Edit Widget.”
• Make your changes, then tap outside the widget to exit.
• You can also move widgets by dragging them anywhere you prefer.

Use widget stacks

In iOS 14, you can create Smart Stacks or your own custom widget stacks to save space on your Home Screen or Today View.

Create a Smart Stack

• Touch and hold an area on the Home Screen or Today View until the apps jiggle.
• Tap the “Add” button and select “Smart Stack.”
• Tap “Add Widget.”

Create your own stack

• Drag one widget on top of another. You can stack up to 10 widgets.
• Tap “Done.”

Edit a widget stack

• Touch and hold the stack, then tap “Edit Stack.”
• Reorder widgets by dragging the three-line handle. Enable Smart Rotate if you want iOS to show relevant widgets throughout the day.
• Swipe left on a widget to delete it. Tap the gray X to remove when finished.

Remove a widget

• Touch and hold the widget you want to remove.
• Tap “Remove Widget.”
• Confirm by tapping “Remove.”