If a different extent is defined, the coordinate system is mapped to the size given regardless of the window size. If an extent value of 200 is set, the coordinates range from -200 to +200. Scaling is performed automatically to fit within the window. It is possible to set different extents for the X and Y coordinates by using a two-element list as input. (SETEXTENT) resets the extent to 1:1 mapping.

Note that each individual turtle, control, or bitmap may have its own screen extent. Thus the lines drawn by different turtles for the same number of turtle steps may be of different lengths if their extents are not the same.

See also EXTENT, SETORIGIN and ORIGIN.