Certain embodiments of the invention may include systems, methods, and apparatus for determining online stress and life consumption of a heat recovery steam generator (HRSG). According to an example embodiment of the invention, a method for assessing components of a HRSG is provided. The method includes receiving HRSG design parameters; determining thermal stress data associated with the one or more HRSG components based at least in part on one or more historical, real-time, or calculated temperature sensor data associated with the one or more HRSG components; and determining cycle-related life consumption data associated with the one or more HRSG components based at least in part on the HRSG design parameters and the determined thermal stress data.