iOS · iPhone & iPad
Turn Off Auto-Brightness on iPhone
Source-checked About 10 minutes
Answer
Open Settings > Accessibility > Display & Text Size, scroll to Auto-Brightness, and turn it off. Apple says this can increase power use.
Decide whether Auto-Brightness is the cause
Auto-Brightness uses the ambient-light sensor, while True Tone, Night Shift, Low Power Mode, device temperature, and HDR content can also change how the display looks. Turning off one control does not disable the others.
Open the correct accessibility screen
In Settings, choose Accessibility > Display & Text Size. Scroll to the bottom; Auto-Brightness is not located beside the normal brightness slider in Display & Brightness.
Turn Auto-Brightness off
Disable Auto-Brightness, return to the Home Screen, and move between brighter and darker surroundings to confirm that the slider no longer changes automatically.
Choose a manual level
Open Control Center and drag the Brightness slider, or use Settings > Display & Brightness. Pick the lowest comfortable level and increase it temporarily outdoors instead of leaving maximum brightness enabled.
Review power and temperature effects
Apple warns that disabling Auto-Brightness can affect battery life. The iPhone may still reduce brightness when it is hot or under other system protections; do not cool it with ice or refrigeration.
Video walkthrough
If it does not work
- If brightness still changes, test with True Tone and Night Shift understood separately, exit Low Power Mode when appropriate, and let an overheated iPhone cool in a shaded room. If the slider is unavailable or the display remains abnormally dim after cooling and restarting, contact Apple Support.
Sources and verification
Checked against official documentation on . Scope: iPhone & iPad.
Follow the linked first-party guidance if labels differ after a platform or app update.