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":
Sarah UNKNOWN
(Abt 1820 Middlesex, England - DECEASED)
John William BULL
(8 Aug 1819 Whitechapel, Middlesex, England - 25 Dec 1908 Barnet, Hertfordshire, England)
└─Jane BULL
(Abt 1857 Highbury, Middlesex, England - 2 Jan 1936 Medway, Kent, England)
George COKAYNE
(Jul 1859 St Luke, London, England - 30 Dec 1943 Chatham, Kent, England)
└─Ronald Kenney COKAYNE
(5 May 1885 Highbury, Middlesex, England - 20 Feb 1964 London, England)
Abt 1820 - DECEASED
John William BULL 
(8 Aug 1819 Whitechapel, Middlesex, England - 25 Dec 1908 Barnet, Hertfordshire, England)