How old do you have to be a child when are buying movie tickets at theatre?

There is no universal age limit for being considered a child when purchasing movie tickets at a theater. It can vary depending on the specific theater chain or movie policy. Most theaters have their own age-based pricing policies, which typically define a child as someone who is under the age of 12, 13, or 14. For example, AMC Theatres considers children to be those who are 12 years old and under, while Cinemark Theatres defines children as those who are 13 years old and under. Regal Cinemas sets the age limit for children at 14 years old and under.

It's important to note that these are general guidelines and the actual age limit may vary from theater to theater, so it's always a good idea to check with the specific theater you're visiting for their specific age policy on child movie tickets.