World War II was the largest and deadliest armed conflict in the history of mankind.
Often abbreviated as WWII or WW2, World War II encircled the globe, forcing nearly every country on Earth to align with one of two massive military alliances: the Axis powers, led by Germany, Italy, and Japan; or the Allies, led by Great Britain, the United States, the Soviet Union, France, and China.
Between the start of the war in September 1939 and its end in August/September 1945, more than 100 million (and possibly as many as 300 million) combatants entered the fray. Many never returned.
Precise casualty numbers for WWII are impossible to determine for most countries, whose stat-keeping capabilities faltered as nations rose and fell, borders changed, populations shifted, and vast numbers of soldiers were killed, wounded, captured, or declared missing in action.
That caveat aside, the most up-to-date estimates calculate that between 70 million and 85 people died in World War II.
That estimate equates to roughly 3-3.7% of Earth's population at the time.
Surprisingly, more than twice as many civilians died in World War II than did members of the military. Current estimates place military deaths between 21 million and 25.5 million people. By comparison, civilian deaths include 29 million to 30.5 million from military and war crimes, plus another 19 million to 28 million due to war-related famine and/or disease.
Top 10 Countries with the Highest Total Casualties in World War II:
Soviet Union — 20 million to 27 million
China — 15 million to 20 million
Germany — 6.9 million to 7.4 million
Poland — 5.9 million to 6 million
Dutch East Indies (Indonesia) — 3 million to 4 million
Japan — 2.5 million to 3.1 million
India — 2.2 million to 3 million
Yugoslavia — 1 million to 1.7 million
France — 600 thousand
The Soviet Union is estimated to have suffered the highest number of WWII casualties. As many as 27 million Soviets lost their lives, with as many as 11.4 million military deaths joined by up to 10 million civilian deaths due to military activity and an additional 8 million to 9 million deaths due to famine and disease. Those totals do not include the more than 14 million Soviet soldiers who were wounded during the war. Among the Soviet Union's 15 republics, Russia withstood the highest number of casualties, with 6,750,000 military deaths and 7,200,000 civilian deaths. Ukraine tallied the second-highest casualties, with 1,650,000 military deaths and 5,200,000 civilian deaths.
China is estimated to have endured the second-highest number of total casualties in WWII. As many as 20 million people died in China, including up to 3.75 million military deaths and 18.19 million civilian deaths. That said, because both China and the Soviet Union were wracked by famine and disease during the war, some experts believe the countries' civilian casualty numbers may be significantly underestimated.
Germany incurred the third-most casualties of World War II, with as many as 7.4 million total deaths.
Also of note is Poland, whose death toll includes an estimated 3.2 million Jewish civilians who died in Nazi concentration and death camps.
The following list includes the total estimated casualties for every country involved in the war.