A software energy estimation methodology is presented that avoids explicit characterization of instruction energy consumption and pre-dicts energy consumption to within 3% accuracy for a set of bench-mark programs evaluated on the StrongARM SA-1100 and Hitachi SH-4 microprocessors. The tool, JouleTrack, is available as an online resource and has various estimation levels. It also isolates the switch-ing and leakage components of the energy consumption.