In C.S. Lewis’s novel The Horse and His Boy, Shasta is introduced as a young boy, and while his exact age is not explicitly stated in the book, he is generally thought to be around 14 years old. Throughout the story, Shasta showcases traits of both youthful innocence and a growing maturity as he embarks on his journey from the land of Calormen to Narnia.
This age estimation comes from hints in the narrative and his interactions with other characters. Shasta demonstrates a certain level of understanding and capability for his age, yet also displays the naivety typical of young adolescents. His character growth throughout the story reflects the transition from childhood to young adulthood, further solidifying the idea that he is around the age of 14.