What is bandwidth required for AM signal?

With full double sideband AM the bandwidth of the modulated signal is twice that of the baseband information signal.

With suppressed carrier single sideband AM the bandwidth of the modulated signal is identical to that of the baseband information signal.

With vestigial sideband AM the bandwidth of the modulated signal is somewhere between the above two cases, depending on how much of the vestigial sideband is included.