In switching mode power supplies we use inductor after the input ac voltage rectified and before the switching and also in the output side we use one before the output capacitor .The inductor help in reducing the ripple current and also prevent suddenly change in the current .so how we calculate the inductance for the input and output sides

 

Got schematic?

Nothing too detailed really, more of a block diagram so we know what type (topology) of switcher you are talking about.

 

In switching mode power supplies we use inductor after the input ac voltage rectified and before the switching and also in the output side we use one before the output capacitor .The inductor help in reducing the ripple current and also prevent suddenly change in the current .so how we calculate the inductance for the input and output sides

Check out this link, I believe it will answer all your questions.

 

Depends on the application, environmental and regulatour requirements.