Full calendar not showing inside bootstrap modal

You should try this :

$('#myModal').on('shown.bs.modal', function () {
   $("#calendar").fullCalendar('render');
});

Here is your fiddle : http://jsfiddle.net/mzAEj/2/

Here is the documentation : http://arshaw.com/fullcalendar/docs/display/render/

---

FullCalender V4

In reading the doc you can read that this command is deprecated,

You've to call calendar.render() is order to have the same behaviour

Extract of code :

  var calendarEl = document.getElementById('calendar');

  var calendar = new Calendar(calendarEl, {
    plugins: [ dayGridPlugin ]
  });

  calendar.render();

Doc source