Real age of Sasha Pieterse in X-Men: First Class
In the movie X-Men: First Class, Sasha Pieterse was:
14 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 X-Men: First Class was released:
January 1, 2011
And the day in which Sasha Pieterse was born:February 17, 1996
Since movies usually don't take more than one year to be released since the beginning of the filming process, Sasha Pieterse may have been one year younger or one year older than the shown age while some scenes of the movie were being filmed.