The Lagrangian experience of a fluid particle in a stirred tank is one of the factors affecting process results ranging from drop size distributions to cell growth kinetics. To examine the Lagrangian experience of a fluid particle with respect to the impeller plane, the mean circulation time (MCT) and the circulation time distribution (CTD) in a stirred tank were studied using the magnetic flow follower method. Two-level factorial designs were used to examine two impellers, a pitched-blade turbine (PET), and a Rushton turbine (RT). Four geometric variables were varied for each impeller : the baffle width, the number of baffles, the off-bottom clearance of the impeller, and the impeller diameter. All four variables, and the interaction between the number of baffles and the off-bottom clearance, had a statistically significant effect (5%) on the MCT for the RT. The significant factors for the PET were the off-bottom clearance, the impeller diameter and the interaction between the clearance and the diameter (30%). The CTDs were mostly bi-modal. Changes in the shape of the distribution were observed for different geometric configurations. This work shows that the Lagrangian experience of a fluid particle depends on the type of impeller used, and on the tank geometry.