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":
Dorothy Cicely JONES
(1894 Surbiton, Surrey, England - 1923 Jesmond, Northumberland, England)
Ulric Henry SMITH
(26 Mar 1890 Clapton, Middlesex, England - 24 May 1958 Eastbourne, Sussex, England)
└─Gordon Ulric SMITH
(13 Mar 1921 Gateshead, Newcastle Upon Tyne, Northumberland, England - 26 Mar 2003 Waltham Forest, London, England)
Francis M. COYLE
(18 Jun 1919 Durham, England - 2007 Wanstead, Essex, England)
1894 - 1923 (29 years)
Ulric Henry SMITH 
(26 Mar 1890 Clapton, Middlesex, England - 24 May 1958 Eastbourne, Sussex, England)