To increase the height of the default face in the current buffer,
type C-x C-+ or C-x C-=. To decrease it, type C-x
C--. To restore the default (global) face height, type C-x
C-0. These keys are all bound to the same command,
text-scale-adjust, which looks at the last key typed to
determine which action to take.
The final key of these commands may be repeated without the leading
C-x. For instance, C-x C-= C-= C-= increases the face
height by three steps. Each step scales the text height by a factor
of 1.2; to change this factor, customize the variable
text-scale-mode-step. As an exception, a numeric argument of 0
text-scale-adjust command restores the default height,
similar to typing C-x C-0.
text-scale-decrease increase or decrease the height of the
default face, just like C-x C-+ and C-x C-- respectively.
You may find it convenient to bind to these commands, rather than
text-scale-set scales the height of the default
face in the current buffer to an absolute level specified by its
The above commands automatically enable the minor mode
text-scale-mode if the current font scaling is other than 1,
and disable it otherwise.