This white paper discusses the major challenges associated with accurately predicting power consumption in FPGAs, namely, obtaining accurate signal activities, static power modeling, and dynamic power modeling, as well as how Altera addresses these challenges through the PowerPlay early power estimator and the Quartus II PowerPlay power analyzer. This paper also presents the accuracy of the model by comparing predicted power consumption with actual silicon measurements using an extensive suite of real-world customer designs. Using these best-in-class power analysis tools, a designer can model the power consumption of their design to within, on average, ±10% accuracy when used with accurate design information.