3 phase calculations

it might just be too early in the morning but I'm getting really confused.


On a 3 phase circuit, I measure 6a 6a and 6a on L1 L2 and L3


I want to work out how many watts it is, so I use rapid tables, set it as 3 phase, 400v line to line and it asks for the amps, is that 6, or is it 18?


The results don't make sense. 


If the loading wasn't equal, is it the sum of all three readings, or an average, or, even, do I clamp all three phases together?


so, using the formula P = √3 × pf × I × V which is fine, but again, is I the total amps per phase, 18, or 6? 



Any help is appreciated