Or create a d2v file and when it finishes successfully then choose the TOOLS menu and hit the PARSE D2V option.
That will open a notepad window with a full description of your project.
Note how your project file starts up on frame 0.
Page down to the end of the notepad window and check the last frame number.
Say you got 196154.
Since your project always starts on 0 that means your movie has 196155 frames in total.
Now divide 196155 for the framerate.
Say your framerate is 25fps as in PAL source.
196155/25=7846,2
7846,2 seconds in total which is the same as saying ~2h10m46s.
Easy huh?