Real age of William Zabka in The Karate Kid, Part II
In the movie The Karate Kid, Part II, William Zabka was:
20 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 The Karate Kid, Part II was released:
January 1, 1986
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.