Real age of Jack Nicholson in Head
In the movie Head, Jack Nicholson was:
30 years old
That was the real age of the celebrity according to our calculation.
The calculation of the shown age took into account the first day of the year in which the movie Head was released:
January 1, 1968
And the day in which Jack Nicholson was born:April 22, 1937
Since movies usually don't take more than one year to be released since the beginning of the filming process, Jack Nicholson may have been one year younger or one year older than the shown age while some scenes of the movie were being filmed.