Six million.

1,000,000 Jews died through privation (starvation and disease) in the Eastern European ghettos the Germans set up.

The systematic killing of Jews began with the invasion of the Soviet Union in June 1941. Special SS and police killing units called the Einsatzgruppen accompanied the invading German army to shoot Jews (men, women and children) and suspected communist officials (adults only). The use of gas (first gas vans, later gas chambers) started near the end of 1941. The Einsatzgruppen started using gas vans to kill Jews because the shootings became too psychologically taxing for the perpetrators. Around 1,500,000 Jews were killed by the Einsatzgruppen in the occupied areas of the Soviet Union.

Between December 1941 and January 1945 an estimated 2.8 to 3 million Jews were gassed upon arrival at one of the six extermination camps that were specifically built for the destruction of the Jews in German-controlled territories. All six of these camps were located in Poland. Gas vans were used in the extermination camp at Chelmno (150,000 to 180,000 killed). The five other camps had gas chambers and they were (in chronological order of start of operation): Auschwitz (900,000 to 1 million), Belzec (600,000), Sobibor (250,000), Treblinka (800,000 to 900,000) and Majdanek (50,000 to 70,000).

An additional 200,000 Jews died in Auschwitz through disease, starvation and gassing after having been initially spared to perform forced labour.

At least 300,000 Jews died in non-extermination camps through disease, starvation and executions.