This tool calculates the bandwidth of a pulse from its duration
Enter the time duration of the pulse and use the drop down menu to select the units (second, millisecond, microsecond, nanosecond).
The bandwidth of the pulse is given by
B = 1/t1
Where the pulse duration t1 is shown in the picture below
As the pulse duration decreases, its bandwidth increases. A pulse duration of 1 second has a bandwidth of 1 Hz. For a narrower pulse with duration of 1 nanosecond, the bandwidth goes up to 1 GHz or 109 Hz.
As the duration of the pulse decreases and goes to zero, the bandwidth increases and tends to ∞. As the duration increases, it tends to looking like a DC signal and the bandwidth goes to 0.