The expiration date of your visa is the last date you could have entered the U.S. on that visa. The length of time you can stay in the U.S. is determined by the admission stamp in your passport. If the admission stamp says that you can stay until August 5th, you can stay until August 5th, regardless of the expiration date of your visa.
Answered on Feb 24th, 2014 at 7:37 PM