Plasticity Index: LL-PLLiquidity Index: LI = (W-PL)/ (LL - PL)Consistency Index: CI = (LL - W)/ (LL - PL)Activity (A) of a soil is the PI divided by the percent of clay-sized particles (less than 2 µm) present.Where, LL=liquid limit, PL = plastic limit, W = natural water content