Building From scratch

Top of saddle to pedal ( crank in line with seat tube) = 1.09 x inside leg (without shoes)
Works for me (and many others) as a good starting point.

Interesting, not used that one before. Gives a frame size up from my earlier caculation. Thats assuming short (165mm) cranks though.

33 x 1.09 = 36

*36 - 2.5(saddle height) - 5(seatpost) - 6.5(165mm crank) = 22.0 frame size (c-c) (56cm)*