I'm used to having the Control button at the bottom left corner of the keyboard. It's a little annoying to be pressing Fn + Tab when I wanted a Control + Tab and the position of the Control button in the new Mac keyboard layout is just very uncomfortable for any finger to reach.

Does anybody know how you can make the Control and Fn buttons change function like how you can change the modifier keys in System Preferences?

  • 5
    Does anyone know why on earth has Apple decided to do this? – mahdix Mar 30 '17 at 8:06
  1. Download and install Karabiner

  2. Open Karabiner Elements and set the Target Device in the dropdown

  3. Map fn to left_control and left_control to fn as below

    Karabiner Elements Map fn to control

  • karabiner is great and does all things – theonlygusti Feb 20 '19 at 4:55

Not sure which OS this started appearing in but in macOS 10.13, this can be customized in System Preferences > Keyboard > Modifier Keys:

System Preferences > Keyboard > Modifier Keys

  • 6
    I'm running 10.13.3 but do not see the fn Key in the modifier key window. Was it removed again? – Spork Mar 27 '18 at 15:26
  • 3
    That's peculiar. I double checked, but see only 4 options. It also doesn't show up on google images for 'modifier keys' (the only exception being the image in this answer). Are you sure it isn't something you've installed? – Spork Apr 4 '18 at 7:43
  • 11
    Sadly this only works to map fn to ctrl but it's impossible to map ctrl to fn. – andresp Jul 2 '18 at 13:21
  • 1
    This, plus binding Caps Lock › Esc, is an absolute gamechanger for Vim – iono Jul 11 '19 at 6:33
  • 1
    Apple doing it again, can remap fn to ctrl but not the otherway around, truly geniuses ahead of its time. – Ivan Castellanos Nov 24 '19 at 1:40

you can use KeyRemap4MacBook


you can find the included prepared settings list at this address:


as you can see there is the setting for Fn Key

  • Thank you! Worked like a charm. And it has many other useful settings, too! – radj Apr 16 '13 at 9:21

You could also add this to private.xml:

<autogen>__KeyToKey__ KeyCode::FN, KeyCode::CONTROL_L</autogen>
<autogen>__KeyToKey__ KeyCode::CONTROL_L, KeyCode::FN</autogen>

See the source for the key code values and predefined settings.


I was happy, but then not as much. I just bought a Logitech K850 keyboard. Has a nice shape to help with wrist issues (for another time). Has keys from left as:

ctrl    fn    alt opt    cmd <butterfly>

Tried Karabiner but it didn't seem to work (tested by using ctrl-F in vi/vim). Then I found this document (https://pqrs.org/osx/karabiner/document.html) which lists a limitation.

Karabiner-Elements cannot modify the fn key on non Apple keyboards such as Logitech keyboards.

Not for Logitech. Ouch. Other suggestions? Back to best buy again? I'm really just looking for a mac layout keyboard with full size keys. I don't care about the num pad, etc. on right side. The K850 looked good except for this issue. Some gentle ergonomics help is good.

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