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":
William Charles BRAID
(1865 Stratford, Essex, England - Mar 1927 Hackney, Middlesex, England)
Elizabeth BUCKLAND
(1869 Ogbourne St Andrew, Wiltshire, England - 14 Jan 1940 Islington, Middlesex, England)
└─Ethel Blanche BRAID
(10 Dec 1895 Islington, Middlesex, England - 21 Mar 1953 London, England)
Charles Henry JAMES
(20 Jul 1899 Islington, Middlesex, England - 21 Apr 1983 London, England)
└─Patricia Elizabeth Ann JAMES
(4 Feb 1930 Islington Barnsbury, London, England - 12 Apr 2015 Farnborough, Kent, England)
Leonard Arthur IVELL
(2 Jun 1929 St Pancras, Middlesex, England - 22 Apr 2019 Bridestowe, Devon, England)
1865 - 1927 (62 years)
Elizabeth BUCKLAND 
(1869 Ogbourne St Andrew, Wiltshire, England - 14 Jan 1940 Islington, Middlesex, England)