LINK TO REPORT In light of a recent U.S. State Department arms control compliance report highlighting Iran’s growing “uranium enrichment activities and stockpile of enriched uranium,” this report presents recent Iranian breakout estimates and compares them to pivotal historical ones, where breakout is defined as the time Iran would need to produce 25 kilograms of weapon-grade uranium (WGU), enough for a nuclear weapon. As of late February 2020, the breakout estimate is 3.8 months, with a range of 3.1 to 4.6 months. This estimate is based on an Institute breakout calculator, utilizing modified ideal cascade calculations, adjusted with results from an earlier multi-year program of complex computer simulations of Iranian breakout, conducted in collaboration with centrifuge experts at the University of Virginia, and supplemented by operational data on Iranian centrifuges.