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":
Richard BROOM
(Abt 1840 Taunton, Somerset, England - 26 Nov 1916 Fazakerley, Lancashire, England)
Clara Jane TANNER
(Jan 1855 Tewkesbury, Gloucestershire, England - 17 Jan 1928 West Derby, Lancashire, England)
└─William Tanner BROOME
(Abt 1886 Coldstream, Northamptonshire, England - 23 Jan 1953 Gronant, Flintshire, Wales)
+ Florence Ada LYNE
(Liverpool, Lancashire, England;9 Sep 1889 - 1 May 1979)
Abt 1840 - 1916 (~ 76 years)
Clara Jane TANNER 
(Jan 1855 Tewkesbury, Gloucestershire, England - 17 Jan 1928 West Derby, Lancashire, England)