Formal:
* Ja, du har ret. (This is the most direct and literal translation.)
* Ja, det er korrekt. (This means "Yes, that is correct.")
* Ja, du har fuldstændig ret. (This means "Yes, you are completely right.")
Informal:
* Ja, du har ret. (This is still the most common way to say it informally.)
* Ja, det er rigtigt. (This means "Yes, that is right.")
* Ja, det er sandt. (This means "Yes, that is true.")
* Ja, helt rigtigt. (This means "Yes, exactly.")
* Ja, selvfølgelig. (This means "Yes, of course.")
The most appropriate way to say it will depend on the context and your relationship with the person you are speaking to.