For the LAP function to operate, start the chronograph/stopwatch feature. Do this by changing the mode (using the MODE button) until you reach the stopwatch/chronograph.  Press the SET/START button to activate the stopwatch.  The LAP function only operates to show periods of elapsed time. It does not serve to store or save lap times. The LAP function will show you how much time has elapsed since you pressed the LAP button, allowing you to time a lap.   To calculate the lap time, press the MODE/LAP button (top right) while the stopwatch is running.  Make a mental note of the time value shown on the display.  When LAP is pressed, the time on the clock is stopped on the display, but the stopwatch/chrono continues to run.  When LAP is pressed again, the stopwatch/chrono display will return back to the total time that has elapsed since the chronograph was started.  Subtract that time value from the value when LAP is pressed and this will tell you your lap time.

To stop the LAP display on the face of the watch, press the MODE/LAP button. Press STOP to stop the chronograph.