3/11

3/11 may refer to:


 * March 11, in month-day date notation
 * 3 November, in day-month date notation
 * 3rd Battalion, 11th Marines
 * March, 11 A.D.; see AD 11
 * November, 3 A.D.; see AD 3
 * 2011 Tōhoku earthquake and tsunami
 * Fukushima Daiichi nuclear disaster, caused by the earthquake and tsunami
 * 2004 Madrid train bombings