Nelson Mandela was imprisoned for approximately 27 years in total.
He was arrested in 1962 and spent time in several prisons, including Robben Island, Pollsmoor Prison, and Victor Verster Prison. Mandela was released on 11 February 1990, after the apartheid government lifted the ban on the African National Congress and began negotiations over South Africa’s political future.
The frequently quoted figure of 27 years covers his imprisonment as a whole, not only his time on Robben Island. Mandela spent about 18 years on Robben Island before being transferred to Pollsmoor in 1982 and later to Victor Verster in 1988.
This distinction explains why “27 years” and “18 years” both appear in accounts of Mandela’s life. Eighteen years refers specifically to Robben Island; 27 years refers to his total time in prison before release.