For my terminal Vim 8.0, I have downloaded this plugin that makes changing font size on the fly easy: https://github.com/drmikehenry/vim-fontsize

Following the instructions, here is how I decided to define my mappings for changing fonts:

nmap <silent> <C>+ <Plug>FontsizeInc
nmap <silent> <C-kPlus> <Plug>FontsizeDec
nmap <silent> <C>- <Plug>FontsizeDec
nmap <silent> <C-kMinus> <Plug>FontsizeDec
nmap <silent> <C>0 <Plug>FontsizeDefault

However, to my surprise, the functionalities are only working for the + and - characters that are not in the NumPad are of my keyboard. When I hit the combinations using + or - form the NumPad, nothing happens. And otherwise, my Vim recognizes the NumPad just normally.

How could I perhaps solve this issue?

  • Those mappings dont look quite right to my eye
    – D. Ben Knoble
    Jan 6, 2019 at 18:47
  • Also the title of your question has nothing to do with it’s body?
    – D. Ben Knoble
    Jan 6, 2019 at 18:47
  • @D.BenKnoble Ooops, my bad, I mistakenly copied and pasted the title from wrong place. Fixed it now. About the mappings, what does not look right? It works perfectly for <C>+, <C>- and <C>0, just not <C-kPlus> and <C-kMinus> Jan 6, 2019 at 18:52
  • The typical syntax is map <LHS> <RHS>, but in your question i see 3 “sides” after the map commands
    – D. Ben Knoble
    Jan 6, 2019 at 18:53
  • @D.BenKnoble Changed that, no effect Jan 6, 2019 at 19:17

1 Answer 1


If I understand your question right, you are working in a terminal. Vim can't change the font size in a terminal. What you see, when pressing Ctrl-+ and Ctrl-- is a functionality of the terminal.

Try it without starting vim.

The plugin you downloaded just changes the guifont.

For this I have the following in my gvimrc:

command! -bar -nargs=0 BiggerFont  :let &guifont = substitute(&guifont,'\d\+$','\=submatch(0)+1','')
command! -bar -nargs=0 SmallerFont :let &guifont = substitute(&guifont,'\d\+$','\=submatch(0)-1','')
nnoremap <M-->        :SmallerFont<CR>
nnoremap <M-+>        :BiggerFont<CR>

Stolen from tpope.

BTW: The {lhs} of the mappings <C>+, <C>- and <C>0 all map a sequence of 4 characters.

BTW-2: I'm not sure that Ctrl-+ and Ctrl-- is mappable at all. If I go into insert mode in gVim and enter Ctrl-V + Ctrl-+ I just get a single +. If I use Ctrl-V + Ctrl-L I get ^L.

  • Thanks, I corrected the mappings, getting rid of that part. Still, the same thing: it does work with <C>+ and <C>-, so it can change the fonts - I don't think it is only the terminal, because if I comment those lines out the re-sizing of the font stops working. It just does not work with the numpad keys Jan 6, 2019 at 19:18
  • 1
    I'm pretty sure your terminal does that, not Vim. My GNOME-Terminal has this. It changes the font size with <C-+> and <C--> even without Vim.
    – Ralf
    Jan 6, 2019 at 19:20
  • You are using Vim in a terminal, not gVim? Which OS?, Which terminal emulator?
    – Ralf
    Jan 6, 2019 at 19:22

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