Carbon nanotubes (CNTs) show great promise as a new class of electronic materials owing to a control on their electrical properties with chirality of the nanotube. On one hand, they can rival the best metal as an interconnect and on the other, a semiconducting nanotube can work as a channel in a nano field effect transistor. The energy band structure and density of states of single wall nanotubes (SWNTs) with different chiralities is reviewed here and then using a diameter dependent model, the electrical conductance of a SWNT, a multiwall nanotube (MWNT) and bundle of CNTs containing MWNTs is simulated and analyzed. It is found that conductance of a CNT depends largely on its geometry.An MWNT shows very high conductance which varies with average tube diameter, length and number of shells in the tube. Similarly, we can playwith the conductance of a CNT bundle by varying its dimensions and density of nanotubes inside the bundle. This study would play an important role in understanding the working of various CNT based electronic devices.