Source: Weinberg, Global History of World War II

90% of German casualties were on the eastern front.

Casualties

USSR                                 20-25 million
China                                       15 million
Poland                                       6 million
Yugoslavia                                2 million
United Kingdom         400,000 thousand
United States              300,000 thousand
Germany                                    4 million
Japan                                          2 million

Total                approximately  50 million