Instead of drawing pixels, you draw a mathematical path and stroke it after creating a custom brush preset.
If you draw arrows often, downloading the "Draw Arrow" script is a life-saver. how to draw an arrow in gimp
This is the most precise manual method and works in any version of GIMP. Instead of drawing pixels, you draw a mathematical
: Choose your line thickness (Line width) and click Stroke . Method 2: The Pro Way (Arrow Script) Instead of drawing pixels