How do you count conductors that are pigtailed (box fill)?
Box fill is covered in article 314.16 of the NEC. The wires are counted by size and type for example 14 awg wire is 2 cubic inches for each hot , neutral and only counted once for the ground, if you have a pig tail that doesn’t add to the count, if you have 12 awg wire it is 2.25 for each with a mix of 14 &amp; 12 the 1 ground wire counted will be the largest or 2.25. The device or switch/ receptacle counts 2x the cu inches of the largest wire connecting to it so if a 12 gauge wire connects the receptacle takes 4.5 cu inches. 
If the boxes have clamps those count 1 time also for the largest wire size . That’s the basics the short pigtails and wirenuts are not added in the amount of the fill.