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":
Thomas BONNER
(Edmonton, Middlesex, England;27 May 1849 - Jan 1934)
Mary BRADFORD
(Between 1858 and 1859 Finchley, Middlesex, England - Oct 1936 Edmonton, Middlesex, England)
└─Dorothy May BONNER
(25 May 1892 Edmonton, Middlesex, England - Oct 1983 Barnet, Essex, England)
George Henry GUNNING
(6 Jul 1887 Poplar, Middlesex, England - Jan 1957 Barnet, Hertfordshire, England)
1849 - 1934 (84 years)
Mary BRADFORD 
(Between 1858 and 1859 Finchley, Middlesex, England - Oct 1936 Edmonton, Middlesex, England)