To watch an R-rated movie in the United States, you generally must be at least 17 years old to attend alone. If you are under 17, you must be accompanied by a parent or an adult guardian who is typically 21 years or older. This adult must stay with the minor for the entire duration of the movie. The exact age enforcement can vary slightly by theater or local law, but the standard guideline set by the Motion Picture Association (MPA) is:

• Under 17 requires accompanying parent or adult guardian (usually 21+)

• Some theaters require the accompanying adult to be 21 or older, and some have policies that no one under 6 or 3 years old is admitted to R-rated movies at any time

• In some cases, theaters may require ID to verify age and enforce these rules strictly

In summary, you must be at least 17 to watch an R-rated movie alone, or be accompanied by a parent or adult guardian aged 21 or older if younger than 17