A portable activity monitoring device comprising a housing having a physical size and shape that is adapted to couple to the user's body, a plurality of sensors, disposed in the housing, to generate sensor data which is representative of activity of the user, processing circuitry, disposed in the housing and electrically coupled to the plurality of sensors, to calculate the one or more activity metrics of the user using the sensor data, wherein the processing circuitry calculates a number of stairs or flights of stairs traversed by the user using the sensor data.