In the lower middle of the workouts screen are two buttons for calibration—calibrate for running and, below it, calibrate for walking.

Nike + iPod collects workout data from a wireless sensor (sold separately) that you attach to your shoe. Before you use it the first time, you need to link your sensor to iPhone.

  • Shoe, meet iPhone. To link the sensor to iPhone, attach the sensor to your shoe, then go to Settings > Nike + iPod > Sensor.

  • Be accurate. To calibrate Nike + iPod, record a workout over a known distance of at least a quarter mile (400 meters). Then, after you tap End Workout, tap Calibrate on the workout summary screen and enter the actual distance you covered.

  • Try again.  To reset to the default calibration, go to Settings > Nike + iPod.