5.48 How can I start Emacs in fullscreen mode on MS-Windows?

Beginning with Emacs 24.4 either run Emacs with the ‘--maximized’ command-line option or put the following form in your init file (see How do I set up an init file properly?):

(add-hook 'emacs-startup-hook 'toggle-frame-maximized)

With older versions use the function w32-send-sys-command. For example, you can put the following in your init file:

(add-hook 'emacs-startup-hook
          (lambda () (w32-send-sys-command ?\xF030)))

To avoid the slightly distracting visual effect of Emacs starting with its default frame size and then growing to fullscreen, you can add an ‘Emacs.Geometry’ entry to the Windows Registry settings. See X Resources in The GNU Emacs Manual. To compute the correct values for width and height you use in the Registry settings, first maximize the Emacs frame and then evaluate (frame-height) and (frame-width) with M-:.

Alternatively, you can avoid the visual effect of Emacs changing its frame size entirely in your init file (i.e., without using the Registry), like this:

(setq frame-resize-pixelwise t)
(set-frame-position nil 0 0)
(set-frame-size nil (display-pixel-width) (display-pixel-height) t)