Real age of William Zabka in Hot Tub Time Machine
In the movie Hot Tub Time Machine, William Zabka was:
44 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 Hot Tub Time Machine was released:
January 1, 2010
And the day in which William Zabka was born:October 20, 1965
Since movies usually don't take more than one year to be released since the beginning of the filming process, William Zabka may have been one year younger or one year older than the shown age while some scenes of the movie were being filmed.