Cervelo frame size

[hrt4me]

I bought a used Cervelo P2K from a co-worker for $400. Of course, he let me ride it before I bought it so I could make sure it fit me. The bike fits, but how do I determine the frame specs (specifically, the actual frame size)? Can I measure this myself, and if so, then where/what do I measure?

[haimtoeg]

Go to the cervelo website frame geometry page, pick 1-2 measurements and compare your bike to the diagram.