During World War II, which contemporary country suffered the most deaths as a percentage of their population?

World War II was the deadliest military conflict in history. An estimated total of 70–85 million people perished, which was about 3% of the 1940 world population (est. 2.3 billion).

Deaths directly caused by the war (including military and civilians killed) are estimated at 50–56 million people, while there were an additional estimated 19 to 28 million deaths from war-related disease and famine. Civilian deaths totaled 50-55 million. Military deaths from all causes totaled 21–25 million, including deaths in captivity of about 5 million prisoners of war.

Belarus was part of the Soviet Union at the time but it is estimated that they lost 2,290,000 people. This accounted for 25.3% of their population at the time. This is the highest out of any country.

Poland lost roughly 17% of its population with 6 million deaths.

The USA suffered just over 419,000 deaths, 0.32% of its population.

Germany suffered 5,700,000 deaths which works out at 8.23% of their population.