Geometry scaling for crevice corrosion is well known and past study has focused on steady?state corrosion with a uniform crevice gap. The scaling method is governed by L/?0.5 the ratio of crevice length (L) to the square root of crevice gap (?). By theory the scaling method can apply to unsteady-state conditions for a one-dimensional crevice including variations of crevice chemistry and potential. This paper is aimed at showing the theory behind the scaling method for a crevice formed on coated pipelines with cathodic protection verifying the scaling method with model simulation results and understanding how significantly biased the scaling method is when applied to a crevice of variable gap.