Add Ctrl key functionality to the space bar.
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This project has been replaced by dual. Dual is a library that allows for the easy creation of custom combo keys such as the Space to Ctrl key mapping created by this project. I recommend all new users follow the instructions on dual's readme page for how to set up a BigCtrl equivalent set-up.


Add full Ctrl key functionality to the space bar on Windows.

Holding the space bar while pressing other keys will act just the same as if you were holding the Ctrl key. If you press and release space without pressing another key then a normal space is returned as expected. This works because the Ctrl key is virtually never used by itself and the space key is rarely used in conjunction with another key. This is particularly useful with the Emacs text editor and other programs that make extensive use of the Ctrl key.


Two features try to help minimize mistakes while typing.

  1. A timeout is used to prevent accidental spaces from being inserted when the space bar key is held down for longer than a quick tap and then released without another key having been pressed. This can happen frequently when a typist is about to press a Ctrl key combo and then decides not to. The default timeout is set to 300ms.

  2. A delay is used to try to ensure a key that was briefly pressed with the space bar is an intended Ctrl combo and not a fast typist starting a new word. If the space bar is released within the specified delay then the normal keys are returned instead of the Ctrl key sequence. The default delay is 70ms.

Both the timeout and the delay settings are customizable in the script version.

How to Run

There are two ways to run the script.

  1. The executable file (BigCtrl.exe) - Just download and double click.

  2. The script file (BigCtrl.ahk) - In order to run the script you will need to download and install AutoHotKey first at AutoHotKey.

Note in either case if you want to use this script with programs that are running under administrator privileges you must also run the script under administrator privileges otherwise the key strokes will not be captured.

Similar Projects

For Linux there are two similar implementations.

  1. At Home Modifier
  2. Space2Ctrl

This project has been incorporated into the ergoemacs keybindings project which provides system-wide ErgoEmacs keybindings.


Licensed under the MIT.