• Should and Ought To

• 
• Should and ought to also function as modals of deduction or speculation when we talk about something we expect to happen.  Should is more commonly used and is less formal than ought to.

  
  

  subject + should/ought to + base verb

  -Jack should be back from the bank by now. He left an hour ago.

  -Jack ought tobe back from the bank by now. He left an hour ago.
  

  (We expect Jack to be back after being away for a long time.)

  
  

  Remember! You can also use should/ought to for obligations.

• Deduction	I should have my new credit card soon. It was mailed a week ago. The bank ought to be open today. It's normally open on Mondays.
  Obligation	We should pay our credit card debt. The bill is due tomorrow. Those cars ought to stop at the stop sign. It's the law.

Source : Alison