To set all four margins in a single call:

chSet 'Mgn' 48 24 36 12

The numbers give the top, bottom, left, right margin settings in points. This property sets the same internal values as the ‘hmar’ and ‘vmar’ properties.

You should leave room for the heading at the top and the X-axis labels and title at the bottom. You may want to increase the left margin if you have big numbers to accommodate in your Y-axis labels. If you only give one number, all four margins are set to this value. They measure from the edge of the chart area to the edge of the plotting region, i.e. the rectangle bounded by the axes.

See also ...
Glossary of Terms