The answer to how old do you have to be to rent a car depends on the country, rental company, and vehicle type. In many destinations, the minimum age to rent a car is 21 years old, although some companies allow rentals from age 18, while others require drivers to be at least 25. Younger drivers may also be subject to additional fees or restrictions on certain vehicle categories. Before making a reservation, travelers should review the rental company's age requirements and policies to ensure they meet all eligibility criteria and avoid unexpected charges.