It looks like Russia had fielded 20,000,000 soldiers. The German Heer or Army was at about 13,000,000.
http://www.feldgrau.com/main1.php?ID=2
Between 1939 and 1945 close to 13 million served in the Heer. Over 1.6 million were killed and over 4.1 million were wounded. Of the 7361 men awarded the initial grade of the highest German combat honor of WWII, the Knights Cross, 4777 were from the Heer making up 65% of the total awarded.
http://www.eisenhowerinstitute.org/p...erienceww2.htm
The populations of the United States and the USSR were about the same, 130,000,000, when both nations went to war within six months of each other in 1941.
Looking only at Anglo-American forces engaged against German soldiers on our two fronts, northwest Europe and Italy, the United States lost 139,380 soldiers (killed and missing) during the conflict. General Eisenhower had just over 3,000,000 men under his command, with about a third of them safely in England, and faced a German Army of less than 1,500,000 of which our forces killed 834,314. At the same time, Soviet armies in excess of 20,000,000 soldiers were fighting German armies totaling 5,700,000 at their strongest and killed 2,415,690 of them as they fought their way out of Russia and on to Berlin.