When Operation Barbarossa began, the Red Army had 2,680,000 in the Western military districts, out of a total strength of 5,500,000, and a theoretical strength of 12,000,000 men which could be mobilized in total. This was against a combined Axis (German + their Allies) force of 3,767,000 arrayed for the operation, giving the Germans a numerical superiority of roughly 1:1.4. Soviet mobilization was not, of course, instantaneous and they were not immediately able to keep pace with losses, so German numerical advantage would peak that November when the Soviets only had 2,200,000 soldiers on the Eastern Front to combat an Axis force of 3,517,000, or 1:1.9, give or take. This was the last phase of the war where the Axis would hold the upper hand by the numbers. By December the mobilization, and shifting of forces from elsewhere, nearly doubled Soviet forces to 4,197,000, and would only continue to rise. A year later the Soviets were 6,124,000 on the Eastern front to 3,500,000 Axis soldiers, and there would be some flux, but they never lost the clear numerical advantage, never fielding less than 150 percent of the numbers that their Axis opponents did, and in the last phase of the war with over 3 times their number.

All numbers are from When Titans Clashed by David M Glantz and Jonathan House.