Should and ought to are very similar and can often replace one another in a sentence. They are used to give advice and to talk about obligation and duty. Should is used more often than ought to.

  • Advice

That’s a bad cough. You should/ought to see a doctor.

  • Obligation

You should/ought to wear a seat belt when you drive a car.

  • Deduction

That should/ought to be him at the door now.

Must can often be used in place of should/ought to but it makes the sentence meaning stronger.

1. ought to

 

Use Examples
advice You ought to drive carefully in bad weather.
obligation You ought to switch off the light when you leave the room.

2. should

Use Examples
advice You should drive carefully in bad weather.
obligation You should switch off the light when you leave the room.