Tmux

How to split panes horizontally and vertically in tmux?

Quick Answer

To split a tmux pane horizontally (creating a pane below), press Ctrl+b followed by " (double quote). To split vertically (creating a pane to the right), press Ctrl+b followed by % (percent sign). You can also use the command tmux split-window.

Ctrl+b+"— horizontal split (creates pane below)

Before:

┌────────────────┐
│                │
│    Terminal    │
│                │
└────────────────┘

Ctrl+b "

After:

┌────────────────┐
│    Terminal 1  │
├────────────────┤
│    Terminal 2  │
└────────────────┘

Ctrl+b+%— vertical split (creates pane to the right)

Before:

┌────────────────┐
│                │
│    Terminal    │
│                │
└────────────────┘

Ctrl+b %

After:

┌────────┬────────┐
│        │        │
│ Term 1 │ Term 2 │
│        │        │
└────────┴────────┘

Detailed Explanation

Splitting panes is one of tmux's most powerful features, allowing you to view multiple terminal sessions side by side. A horizontal split creates a new pane below the current one, stacking them vertically.

Note on Terminology

tmux's terminology can be confusing: a "horizontal split" creates a horizontal line dividing panes vertically (one above the other). This is why some users prefer to use the term "split horizontally" to mean "create a horizontal divider."

Using keyboard shortcuts:

Ctrl+b " - Split current pane horizontally (create pane below)
Ctrl+b % - Split current pane vertically (create pane to the right)

Using tmux commands:

Ctrl+b : then type split-window - Split horizontally
Ctrl+b : then type splitw - Shorthand for split-window

From the command line (outside tmux):

tmux split-window -t session:window.pane - Split specific pane horizontally

Useful options:

split-window -h - Split vertically (side by side)
split-window -v - Split horizontally (explicit)
split-window -p 25 - New pane takes 25% of space
split-window -c "~/projects" - Set starting directory
split-window "top" - Run command in new pane

Pro Tip

Create a custom key binding for splitting windows while staying in the same directory by adding these lines to your ~/.tmux.conf:

bind '-' split-window -c "#{pane_current_path}"
bind '|' split-window -h -c "#{pane_current_path}"

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