How do I make the indent width automatically match the tabstop setting without keeping them in sync manually?

Explanation

Setting shiftwidth=0 tells Vim to use the value of tabstop wherever shiftwidth would normally be consulted — for the > and < operators, <C-t> and <C-d> in insert mode, and auto-indent. This eliminates the common frustration of having tabstop and shiftwidth drift out of sync when switching between projects with different indent styles.

How it works

• Normally shiftwidth controls indent size and tabstop controls how wide a tab character renders. They are independent, so you must set both.
• When shiftwidth=0, Vim substitutes tabstop for shiftwidth internally — the two are always equal, automatically.
• You only need to set tabstop (or softtabstop if you use space-based indentation) and the shift operators will follow.

Example

Instead of:

set tabstop=4 shiftwidth=4 expandtab

You can write:

set tabstop=4 shiftwidth=0 expandtab

Now if you later change tabstop to 2 for a different file, > and < will automatically indent by 2 — no need to update shiftwidth.

Tips

• This is especially useful in FileType autocmds: setlocal tabstop=2 shiftwidth=0 applies one setting and indentation follows automatically
• To check the effective shiftwidth at runtime: :echo shiftwidth() — the shiftwidth() function respects the zero-fallback and returns the actual value that will be used
• The zero-value behavior was added in Vim 7.3.693 and is available in all modern Vim/Neovim versions