 Corrosion is a major issue for engineers and scientists as it can cause structural failure, chemical processing plant shutdowns, and metal degradation. Immersion tests are commonly used to measure corrosion rates, however these tests often fail to account for changes in the surface area of the corroded material. This paper presents a new formula to accurately measure corrosion rates using immersion tests, taking into consideration any changes in the surface area of the corroded material. This formula can be used to improve the accuracy of experimental data and the analysis and modelling of corrosion phenomena. This article was authored by Francisco Mallorette and Xinxi Yang.