From Xojo Documentation
The height of the printable area on the page (in pixels). The height is the PageHeight minus the margins.
This example displays the Page Setup box and then displays the page size, printable area, and margins in Label controls. Results, of course, depend on the page size that the user selects. Since PageLeft and PageTop are the horizontal and vertical margins as measured from the printable area rather than the edge of the page, they are negative.
Var p As PrinterSetup
p = New PrinterSetup
If p.PageSetupDialog Then
settings = p.SetupString
Label1.Value = "PageLeft=" + p.PageLeft.ToString
Label2.Value = "PageTop=" + p.PageTop.ToString
Label3.Value = "PageHeight=" + p.PageHeight.ToString
Label4.Value = "PageWidth=" + p.PageWidth.ToString
Label5.Value = "Height=" + p.Height.ToString
Label6.Value = "Width=" + p.Width.ToString
Label7.Value = "Computed height=" + Str(p.Height - 2 * p.PageTop)
Label8.Value = "Computed width=" + Str(p.Width - 2 * p.PageLeft)