I have only one Head racquet (Head 660 Lady) which is nominally 660 square centimeters (102 sq. inches).
According to my measures (inside the hoop), the head area is 661 square centimeters, which is practically as advertised (I calculated the area of "ideal" ellipse, while the actual shape is slightly like the teardrop, so that may cause slight variations).
For Wilson BLX Pro Open I calculated 636/98, slightly less than advertised 645/100.
For Babolat Pure Drive, I got exactly 645/100, as advertised.