1. A method for calculating localized corrosion of an electrically conductive article comprising: (a) placing a working electrode, a reference electrode, and a counter electrode in an environment of interest, wherein the working electrode has substantially the same composition as the electrically conductive article; (b) placing the working electrode under potentiostatic control; (c) measuring a current transient between the working electrode and the counter electrode; (d) switching the working electrode to open circuit potential; (e) measuring a potential transient substantially over a duration of a localized corrosion event; (f) calculating the localized corrosion based on the measured potential transient and the current transient, where at least one parameter is calculated which parameter is selected from the group consisting of: i) the rate of penetration of a pit, based on a time rate of change of the monitored transient; and ii) a rate of penetration for multiple pits, based on a sum of ratios: 1 R = ∑ n = 1 n ⁢ ( 1 R n ) where each R n is given substantially as R n ⁡ ( t + Δ ⁢ ⁢ t ) = R ⁡ ( t + Δ ⁢ ⁢ t ) · ∑ n = 1 n ⁢ P ⁢ ⁢ D n 2 ⁡ ( t ) P ⁢ ⁢ D n 2 ⁡ ( t ) .