Following a discussion of 2 line vs 3 line on TMP, I wrote a spreadsheet to calculate the difference.  You can set the number of men in each battalion, including the split between the front 2 firing ranks of a French battalion, and those in reserve who fill gaps, as well as the assumed accuracy that will cause a wound severe enough to put a man out of battle.

It is fairly crude on maths, as it makes a number of assumptions:

  1. Kill rate as a % stays constant.
  2. Those filling gaps do so before the next volley
  3. A straight 1 on 1 firefight
  4. Wounds are cause simultaneously – ie it calculates hits before subtracting wounds.  If you want one side to fire first, reduce the strength of the other to start.

The way it calculates the remaining men in the 3 rank bn is by applying all casualties to the 3rd rank (non firers).  When this reaches zero it subtract the overkill from the firing ranks (well it adds the negative number).

Casualty calculator

Excel 97 version

Excel 97 version