The deterioration models for reinforced concrete structures include a period for time to corrosion cracking: time from initiation of corrosion to first cracking. Theoretical equations for determining the time to corrosion cracking have been presented but never validated. This paper reports on a study which was initiated to validate or modify a set of theoretical equations for field linear polarization, unguarded and guarded, corrosion rate devices. The test variables included six corrosion rates, two concrete cover depths, two reinforcing steel bar diameters and spacings, two exposure conditions (indoors and outdoors), and one design concrete strength (water to cement ratio). Influence of temperature and chloride content on the measured corrosion rates are presented. Corrosion rates increase with increasing chloride content and corrosion rates vary significantly with annual changes in temperature, highest in the spring and lowest in the winter. Measured metal loss measurements were compared with the calculated metal loss based on monthly corrosion rate measurements for both devices. The 3LP device significantly over-estimated the amount of metal loss and the Geocor 3 device significantly under-estimated the amount of metal loss based on average monthly measurements. The theoretical time to corrosion cracking equations significantly under-estimated the time to corrosion cracking using a uniform corrosion rate based on the measured metal loss.