As a follow-up to a comment of mine on a February 2009 thread at my monarchist forum on the engagement of Crown Princess Victoria of Sweden about relationships between reigning European monarchs eventually growing more distant as unequal marriages continue to be the norm, I prepared this table.
I omitted the two principalities since those relationships are more distant. c=cousin, r=removed, so "4c1r" means "fourth cousin once removed." The table should be read, "(name at left) is the (relationship) of (name on top)," e.g., Grand Duke Henri is the nephew of King Albert II. The most recent common ancestor, from whom the relationship is calculated, is given in parentheses; keys to those abbreviations are below.
This chart became outdated with the abdication of Queen Beatrix of the Netherlands in favour of her son King Willem-Alexander on 30 April 2013, and even more so with the abdication of King Albert II of the Belgians in favour of his son King Philippe on 21 July 2013 and then the abdication of King Juan Carlos of Spain in favour of his son King Felipe VI in June 2014. For an updated version, see Peter's chart at my forum (key).
| Elizabeth II | Margrethe II | Carl XVI Gustaf | Juan Carlos I | Beatrix | Harald V | Albert II | Henri | |
| Elizabeth II | 3c (QV or C9) | 3c (QV) | 3c (QV) | 5c1r (FF1MS) | 2c (E7) | 3c (C9) | 3c1r (C9) | |
| Margrethe II | 3c (QV or C9) | 1c (G6A) | 3c (QV) | 2c1r (FF2MS) | 2c (F8) | 2c (F8) | 2c1r (F8) | |
| Carl XVI Gustaf | 3c (QV) | 1c (G6A) | 3c (QV) | 3c (GVWP) | 2c1r (O2) | 2c1r (O2) | 3c (O2) | |
| Juan Carlos I | 3c (QV) | 3c (QV) | 3c (QV) | 4c (FLMS) | 3c (QV) | 4c (LP) | 4c1r (LP) | |
| Beatrix | 5c1r (FF1MS) | 2c1r (FF2MS) | 3c (GVWP) | 4c (FLMS) | 3c1r (WN) | 3c1r (WN) | 4c (WN) | |
| Harald V | 2c (E7) | 2c (F8) | 2c1r (O2) | 3c (QV) | 3c1r (WN) | 1c (CV) | 1c1r (CV) | |
| Albert II | 3c (C9) | 2c (F8) | 2c1r (O2) | 4c (LP) | 3c1r (WN) | 1c (CV) | uncle (L3) | |
| Henri | 3c1r (C9) | 2c1r (F8) | 3c (O2) | 4c1r (LP) | 4c (WN) | 1c1r (CV) | nephew (L3) |
C9=King Christian IX of Denmark (1818-1906) and Louise of Hesse-Kassel
CV=Prince Carl of Sweden, Duke of Västergötland (1861-1951) (son of O2) and Ingeborg of Denmark (daughter of F8)
E7=King Edward VII of Great Britain (1841-1910) (son of QV) and Alexandra of Denmark (daughter of C9)
F8=King Frederik VIII of Denmark (1843-1912) (son of C9) and Louise of Sweden
FF1MS=Grand Duke Friedrich Franz I of Mecklenburg-Schwerin (1756-1837) and Luise of Saxe-Gotha
FF2MS=Grand Duke Friedrich Franz II of Mecklenburg-Schwerin (1823-1883) (grandson of FLMS) and Augusta of Reuss (Danish descendants) or Marie von Schwarzburg-Rudolstadt (Dutch descendants)
FLMS=Friedrich Ludwig of Mecklenburg-Schwerin (1778-1819) (son of FF1MS) and Elena Pavlovna of Russia (Dutch descendants) or Karoline of Saxe-Weimar-Eisenach (Spanish descendants)
G6A=King Gustaf VI Adolf of Sweden (1882-1973) and Margaret of Great Britain
GVWP=Georg Victor, Prince of Waldeck and Pyrmont (1831-1893) and Helene of Nassau (daughter of WN)
L3=King Leopold III of Belgium (1901-1983) and Astrid of Sweden (daughter of CV)
LP=King Louis Philippe of the French (1773-1850) and Marie Amelie of the Two Sicilies
O2=King Oscar II of Sweden (1829-1907) and Sophia of Nassau (daughter of WN)
QV=Queen Victoria of Great Britain (1819-1901) and Albert of Saxe-Coburg
WN=Wilhelm, Duke of Nassau (1792-1839) and Pauline of Württemberg
Inspired to attempt a bigger challenge, I then prepared this similar table for 1914:
Relationships of European Sovereigns in 1914
I am grateful to forum member Peter for his help in revising and refining these tables. Peter has also prepared many of his own charts which are available at the European Royal Genealogy section of my forum.