Brightness keys not working on your Mac

Why it happens

The top row of keys can either control your Mac (brightness, volume) or act as plain F1 to F12 keys for apps. If they're set to act as F-keys, pressing them does nothing to the screen. Most external monitors also ignore these keys, because they're set with the monitor's own buttons.

How to fix it

1. Hold the fn key (it may show a globe), and press F1 or F2. If brightness changes, the keys are set to work as function keys.

2. To fix that for good, open Keyboard settings, click Keyboard Shortcuts, choose Function Keys and turn off Use F1, F2, etc. keys as standard function keys.

   Keyboard›Keyboard Shortcuts…›Function Keys›Use F1, F2, etc. keys as standard function keys

3. Meanwhile, you can always set brightness with the slider. Open Displays settings and drag Brightness.

   Displays›Brightness

Still not fixed?

1. On an external monitor, use the buttons on the monitor itself or its on-screen menu. Apple displays are the exception: they show a Brightness slider in Displays.

2. On a MacBook Pro with a Touch Bar, brightness is in the strip of controls on the right end of the Touch Bar. Holding fn shows the F-keys instead.

3. If your keyboard isn't made by Apple, its top keys may not control brightness at all. Use the Display slider in Control Center instead.

4. If brightness keeps drifting after you set it, turn off Automatically adjust brightness in Displays.

   Displays›Automatically adjust brightness

5. If F1 and F2 do nothing even with fn held, while other keys work, the keyboard may have a fault. That's hardware, so contact Apple Support or a repair shop.