In general, most roller coasters have a minimum age requirement of 42 inches or taller. However, some coasters may have a higher age requirement, such as 48 inches or 54 inches. Additionally, some coasters may have other restrictions, such as requiring riders to be accompanied by an adult.
It's always a good idea to check with the amusement park or ride operator to confirm the specific age requirements and restrictions for a particular roller coaster before riding.