On 18 February 2021, the Mars 2020 Perseverance rover and Ingenuity helicopter successfully landed inside Jezero Crater. At 1026 kg, Perseverance is the largest, most sophisticated rover ever delivered to another planet. This event marked the ninth successful landing and fifth rover to be delivered at Mars. The Program to Optimize Simulated Trajectories II, a trajectory simulation tool, was the prime entry, descent, and landing performance simulation for Mars 2020. This paper presents comparisons between the flight telemetry and the simulation predictions. In general, approximately 90% of the as-flown values were within [Formula: see text] (standard deviations) of the preflight simulation predictions, and the anomalies are discussed in the paper. These comparisons are important in order to understand how each of the individual models and the integrated simulation as a whole performed. This information is fed forward to future missions, which benefit from knowing where additional resources or studies are needed and where uncertainties may be reduced to enable improved performance.