I have heard on the forum about the different ways the tennis companies measure their racquet head sizes (i.e. Head - from outside of the frame, Wilson - from inside the frame). Please, let us know to avoid confusion: Head? Wilson? Prince? Babolat?

We have yet to determine how the various manufacturers measure head size and will post here once we find out. Here is a rough guide that you can use to measure the head size of your racquets at home. This rough guide comes courtesy of one of our Supervisors. Jason responds: This a rough estimate. The real equation takes a full piece of paper to figure out. I tried this equation on the Wilson nCode nPro Open Midplus racquet and I got 100.05 sq inches. Wilson lists this racquet with a headsize of 100 sq. inches - so the equation got me close enough! The equation used is the basic equation to measure an ellipse: (Pi X Axis 1 X Axis 2)/4 Axis 1 = diameter of the racquet Axis 2 = length of the head size (down the center) **All measurements should be taken from the inside of the frame** TW Staff

You'd better ask some physics guy to do a real world measure (I think he will do a triangle approximation given that he got a very clear photo of the racket. ) of course. Only the tech people at Head have a different opinion on that.

Actually, all you need is the circumference of a circle (or an ellipsoid) to measure the surface area of that circle: A = pi x r squared; you find the radius by knowing the circumference and dividing by pi (3.14159)...junior high math...

That's right. In fact, it is mathematically impossible to calculate the area of a racquet head with just a few parameters, due to the fact that it has an irregular shape. If I want to estimate the size, I would take out a graph paper and count the number of squares, i.e. integration the hard way.

I'm sorry, but it sounds like you need a refresher course in junior high math. A circle and an ellipse of the same circumference have different areas. A circle is a special case of an ellipse: maximum area given the circumference. So the area of an ellipse given a circumference is necessarily smaller than that of a circle.

I remember measuring the circumference on the inside of the racquet head with some string, measuring the length and dividing it by four. I came to 8.4 inches (or, I guess 84) for my 85 sq in Wilson, so I guess it's pretty accurate? However, I'm sure some smart PhD in mathematics about to receive a Nobel Peace Prize will debunk this theory in the wink of an eye...