The paper length is not relevant since the chart flows from one page to the next.
Mobile
in.
mm
Portrait
2.75
70
For smart phones, not for printing
Landscape
5.5
140
For smart phones, not for printing
USA & Canada
in.
mm
Letter Portrait
8.5
216
Also Legal Portrait
Letter Landscape
11
279
Legal Landscape
14
356
Also Ledger Portrait
Ledger Landscape
17
432
International
in.
mm
A5 Portrait
5.82
148
A4 Portrait
8.25
210
Also A5 Landscape
A4 Landscape
11.71
297
Also A3 Landscape
A3 Landscape
16.54
420
The Text+ programs assume that the right and left margins are each about 25mm (1/2 inch) wide.
On the Format for Printing page, differences in page margins can be accommodated by the "fudge factor":
Mother: Sophia GILES
(Abt 1823 London, England - 18 Jun 1897 Rotherhithe, Surrey, England)
Samuel GILES
(London, England;24 Dec 1859 - 10 Apr 1915)
Alice Maud Mary WEBSTER
(12 Jul 1862 Southwark, Surrey, England - 3 Aug 1935 Rotherhithe, Surrey, England)
└─Violet Mary Ann GILES
(Abt 17 Dec 1901 London, England - Nov 1982 Bromley, Kent, England)
Charles HOWARD
(18 May 1896 Walworth, Surrey, England - 30 Nov 1977 Bickley, Kent, England)
└─Irene Violet HOWARD
(30 Jan 1923 Southwark, Surrey, England - 10 Jul 2006 Coventry, Warwickshire, England)
1859 - 1915 (55 years)
Alice Maud Mary WEBSTER 
(12 Jul 1862 Southwark, Surrey, England - 3 Aug 1935 Rotherhithe, Surrey, England)