How do I edit an existing buffer in a new tab in vim?

"You wish to open a buffer in a new tab ?

Split up the screen (Ctrl-W s), take up a window, and Ctrl-W T"

"You can accomplish this by combining the tab command with the sb[uffer] command.

First you'll need to know the buffer id of the buffer you wish to open in a new tab. You can find this out with the ls command:

:ls
1 %a ""foo"" line 1
2 ""bar"" line 0

Once you have the id, you can easily open it in a new tab using:

:tab sb 2

The sb command normally opens the given buffer in a new split window, but the tab command causes it to open in a new tab, instead.

The tab command also allows you to specify where in the tab list the new tab should be created. For example, :0tab sb 2 would result in the new ‘bar’ tab appearing at the beginning of the list instead of after the current tab."

"Just add some point which other guys didn't mention.

current window to new tab

If have multiple window, <C-W>T will move this window to new tab. However, this shortcut only for ""Window"", not ""buffer"". If prefer this style, :sp or <C-W>s to duplicate current buffer to one more window, then <C-W>T to move it to new tab.

4 keystrokes or 7 keystrokes.

current buffer to new tab

:tabe % to open new tab for current buffer.

7 keystrokes.

buffer to new tab

If use CtrlP plugin, also could use ""CtrlPBuffer"", then with <C-t> shortcut to open it with new tab page.
This style, easily to switch to different buffers.

With shortcut of ""CtrlPBuffer"", 4 keystrokes or more."
"Just add some point which other guys didn't mention.

current window to new tab

If have multiple window, <C-W>T will move this window to new tab. However, this shortcut only for ""Window"", not ""buffer"". If prefer this style, :sp or <C-W>s to duplicate current buffer to one more window, then <C-W>T to move it to new tab.

4 keystrokes or 7 keystrokes.

current buffer to new tab

:tabe % to open new tab for current buffer.

7 keystrokes.

buffer to new tab

If use CtrlP plugin, also could use ""CtrlPBuffer"", then with <C-t> shortcut to open it with new tab page.
This style, easily to switch to different buffers.

With shortcut of ""CtrlPBuffer"", 4 keystrokes or more."

"If you are using fzf.vim plugin. You could list the buffers using :Buffers, then select the specific buffer with <C-j/k> (or filter by typing buffer number or file name), then use <C-t> to open the selected buffer in new tab.

I use below mapping to quickly list the buffers:

nnoremap <leader>b :Buffers<CR>"