Pakistan has a nuclear weapons stockpile of 110 to 130 warheads, an increase from an estimated 90 to 110 warheads in 2011. With several delivery systems in development, four operating plutonium production reactors, and uranium facilities, the country’s stockpile will likely increase over the next 10 years, but by how much will depend on many things. Two key factors will be how many nuclear-capable launchers Islamabad plans to deploy, and how much the Indian nuclear arsenal grows. Based on Pakistan’s performance over the past 20 years and its current and anticipated weapons deployments, the authors estimate that its stockpile could realistically grow to 220 to 250 warheads by 2025, making it the world’s fifth-largest nuclear weapon state.