The default margin settings are determined by the printer and/or plotter you install under Windows. There are variations for many printing devices that require different margin settings. For example, some printers have non-printable areas as small as 1/8" (.5 cm) on each side, while other devices, such as large plotters, may have up to a 2 1/2" (5.2 cm) non-printable area on each edge. Also, these non-printable areas may not be equal for top, bottom, left and right margins.
Therefore, to ensure optimal margin settings, check the documentation for your device to verify specific settings. It is recommended that you give yourself an additional 1/4" (.7 cm) of leeway beyond the printer's limitations in order to compensate for variances in loading paper into the device.