The word “dad” can be capitalized depending on how it is used in a sentence or title. When used generically in a sentence such as: “my dad said to visit him,” then the word dad is lowercase because it is a generic noun.
Correct: My dad is the best.
However, if you are addressing your dad directly, such as when asking a question, then you should capitalize the word dad.
Correct: Can I go to the movies, Dad?
For more title capitalization questions, use our free title capitalization tool here.