OK, lets move up a level. If, for the French army we have approximately 1 infantry or cavalry stand per division with the Corps as the main organization unit, the our full Army of the Rhine has five prime units and 23 divisional stands plus artillery (Three more Corps of 14 divisions are in Alsace with MacMahon); what about the Germans?
A full-strength German infantry division has 12,000 bayonets plus guns and a regiment of horse. Our French division has just less than 10,000. A German Corps, on the other had, is ordinarily two divisions plus extra artillery; a French Corps (with variation) is more typically 3 divisions. The full German OOB on 1 August is roughly 16 Corps with more variation in the detail of the allied Corps.
At Gravelotte, Five French Corps were present, most of the Army of the Rhine made an appearance. For the Germans, bits of seven or eight Corps attended.
Something that does occur to me is that, since the armament and tactics of the two armies were so different, I can reasonably get away with a stand per division plus artillery stands for the Corps. Size is only one performance factor, anyway, and not the most important.