CrackMacHorizontal lines on a MacBook screen: what they mean and what to do
Horizontal lines across a MacBook screen usually mean the panel, the connection along its edge or the display cable is damaged. That's typical after a drop, pressure on the closed lid or a spill. A quick screenshot test tells you for sure. Lines that show up in a screenshot are software or graphics. Lines that don't are in the display itself.
Not ready to pay for a repair? If the damage sits along an edge, you can block off the broken part and keep using the rest.
Three tests
- The screenshot test. Press Command-Shift-3 and open the screenshot on a phone or another computer. If the lines aren't in it, the display hardware is the cause.
- The monitor test. Connect an external monitor. Lines on the built-in screen only point to the panel or cable. Lines on both point to the graphics.
- The lid test. Slowly tilt the lid back and forth. Lines that appear, move or vanish with the angle point to the display cable.
The free screen test shows solid colours full screen, so you can see exactly where the lines are.
What the lines look like, and what they mean
| What you see | Likely cause |
|---|---|
| One thin line, always in the same place | A damaged row in the panel. It won't heal, but often stays as it is. |
| A band of lines along the top or bottom edge | Panel damage near that edge, typical after a drop or a cracked corner |
| Lines that flicker or move with the lid | The display cable. Cable repair. |
| Black horizontal lines with a dark area | A cracked LCD layer, often spreading. Cracked and black. |
| Coloured or glitchy lines that also appear in screenshots | Graphics or software. Restart and update macOS. |
| Lines after a spill | Liquid damage. What to do right now. |
Vertical lines have their own causes. Here's the guide to vertical lines, and pink or green ones are in pink or green lines.
If the screenshot shows the lines too
- Restart the Mac. Glitchy lines from a frozen graphics state often go away.
- Update macOS in System Settings, General, Software Update.
- Try safe mode. If the lines go away there, an app or login item is the cause.
- Run Apple Diagnostics. On Apple silicon, hold the power button at startup and press Command-D at the startup options. On Intel, hold D at startup.
If the damage runs along one edge, CrackMac can keep windows, menus and the pointer off it. There's a free 30-minute trial.
If it's the display
A damaged panel needs a new display assembly. Here are the prices by model. If the lines stay in a band along the top or bottom and the rest of the screen is clean, you can block that band off and keep using the Mac. Here's how to disable part of the screen.
Quick answers
Why are there horizontal lines on my MacBook screen?
Usually because the panel, its connection along the edge or the display cable is damaged, often after a drop, pressure or a spill. Less often it's the graphics or a macOS glitch. A screenshot test tells which: lines that don't appear in a screenshot are in the display.
Can horizontal lines on a MacBook screen be fixed?
Lines caused by software go away with a restart or an update. Lines caused by hardware don't go away by themselves; the fix is a new display assembly or, when the lines change with the lid angle, sometimes the display cable.
Do horizontal lines on a MacBook screen spread?
Lines from a damaged panel often stay put for a while and then multiply, especially after another knock or with heat. A band of lines along one edge often grows into a dead strip.
Lines in a band at the top or bottom?
When horizontal lines fill a strip along one edge and the rest of the picture is clean, CrackMac paints that strip black and moves the menu bar, windows and pointer onto the working part.
- Works on macOS 13 or later, Apple silicon and Intel.
- Free for 30 minutes of use, then a one-time price. No subscription.
- A refund within 7 days, no questions asked.