The two chains of DNA are coiled in a right-handed helicle fashion. The pitch of the helix is 3.4nm and has a diameter of 2 nm. In the B-form of DNA, the distance between a bp in a helix is approximately 0.34nm which means there are about 10 nucleotides present in a complete turn.
The total length of DNA molecule in nm = 1.1×109 nm.
The approximate number of base pairs = 0.34=1.1×109=3.3×109