Default 50/50 window proportions might not be exactly what you're looking for, and there are some options for changing sizes.
Ctrl + w followed by = will equalize the height and width of all open windows. This is really useful when you just resized the Vim window and the height of your windows got all messed up.
The :resize command increases or decreases the height of a current window, while :vertical resize will adjust the width of the window. You can use these as follows:
- :resize +N will increase the height of a current window by N rows
- :resize -N will decrease the height of a current window by N rows
- :vertical resize +N will increase the width of a current window by N columns
- :vertical resize -N will decrease the width ...