H1B validity calculation - Please help

[jnk_in]

Hi All,

I got my first H1B on Nov 2010.
My first visa stamping is done on Mar 2011.

I first entered USA on 12-Sep-2011.

I have spent 3 yrs and 3 months now in USA.

Now I am going to apply for extension. Will I be getting extension till sep 2017 ( based on the time spent in USA) or it will be only till Nov 2016 ( based on the first H1B approval).

Can someone please help me on this? Appreciate your help on this.

Thanks,NJ.