To fix black borders on a TV or display, you need to resolve the mismatch between the source device's output and the display's aspect ratio or overscan settings. Black borders usually appear because the TV is adding overscan or the picture size is set incorrectly, rather than displaying the full signal from your device.
Why you see black borders on your TV or display
Black borders on a TV or external display usually come from a mismatch between the device’s output aspect ratio or zoom and the TV’s overscan or picture-size settings. On Apple devices, a mirrored or externally displayed image may show black borders when overscan or underscan is being applied. On TVs, black bars on the left and right commonly mean the incoming signal aspect ratio does not match the TV screen aspect ratio.
Fix black borders on a Mac
If you are using a Mac, the black borders can often be corrected by adjusting the Underscan setting. To do this, open the Apple menu, go to System Settings > Displays, select the TV in Display Settings, and adjust the Underscan setting if it is available. If your Mac does not show an Underscan setting, Apple says to check the TV’s own settings instead, as the display itself may be applying overscan.
Fix black borders on an Apple TV
Apple TV devices have specific settings to correct black borders caused by overscan. For Apple TV 4K or Apple TV HD, the exact menu path is Settings > AirPlay and HomeKit > AirPlay Display Underscan. For Apple TV (3rd generation) or Apple TV (2nd generation), the exact menu path is Settings > Audio & Video > Adjust for AirPlay Overscan. These settings are designed for when you are using AirPlay to mirror or extend your display to the TV.
Adjust your TV or projector's picture settings
When the connected source does not provide an Underscan option, Apple’s guidance is to use the display’s own size or overscan controls. Check your TV’s aspect ratio, zoom, or overscan settings in its on-screen menu. Samsung's support page for this issue is specific to TVs with bars on the left and right.
Frequently Asked Questions
Why do black bars appear on the sides of my TV?
This is normal for many films and is not a setting that can be "fixed" without cropping the image.
Can I fix black borders on an iPhone or Android?
The documented steps cover Mac and Apple TV only. If you are casting from a mobile device, the issue is usually controlled by the TV’s own aspect ratio or overscan settings.
Will updating my TV’s firmware remove black borders?
Updating firmware is unlikely to change the aspect ratio or overscan behavior that causes black borders; adjusting the display’s picture settings is the primary solution.
What if I see black borders only when using TV casting and streaming apps?
If black borders appear only when using TV casting and streaming apps, the app itself may be sending a signal with a specific aspect ratio (such as a movie in 21:9). The TV’s picture size or zoom settings can often stretch or fit the image to fill the screen, though this may crop part of the picture.
Do HDMI cables cause black borders?
A faulty or loose HDMI cable can cause display issues, but it rarely causes consistent black borders around the entire image. If you suspect the cable, try a different one, but the most likely cause remains a setting mismatch between the source and the TV.
