WWII: ratio of Allied to Axis manpower 1939-1945

Differences in army sizes and military manpower of nations played a crucial role in the Second World War. While the Allied nations and their colonies or dominions had significantly larger combined populations than the Axis powers, the difference in the number of service personnel at their disposal was much smaller, especially in the war's early phase.

Eastern Front

With the annexation of Poland, Czechoslovakia, and the Balkans by mid-1941, the Axis forces in the Eastern theater outnumbered the Soviet Union. Following the launch of Operation Barbarossa in June 1941, the Axis forces were then able to push the Soviets as far back as Moscow - when the frontline stabilized, the Soviet Union was able to call upon its larger population to replenish and reinforce its ranks, eventually outnumbering the enemy the following year. Many Soviet women were also drafted in to fight, with notable and decorated examples serving as snipers, pilots, and artillery operators.

Western Allies

The combined Allied forces in the Pacific and on the Western European fronts (i.e. those mostly led by the UK and U.S.) always outnumbered the Axis powers. This was largely due to the increased mobilization of the United States military after 1941, particularly in the build up to the Invasion of Normandy on June 6, 1944, as well as the redistribution of Germany's forces from the Eastern to Western fronts in response to this, and the withdrawal of Italy from the war in late 1943. Japan did ramp up its conscription efforts in the final years of the war, but it was not enough to offset the huge numerical advantage of the Allies.