Here, we present a protocol to perform a time-kill assay (TKA) to quantify bacterial burden at multiple time points using colony-forming units and most probable number readouts simultaneously. We describe steps for preparing inoculum, experimental conditions, and sampling bacterial counts. We then detail procedures for quantification and analysis. TKAs provide longitudinal data reflecting the dynamics of the antibiotic effect over time against a planktonic culture and quantify the concentration-effect relationship. For complete details on the use and execution of this protocol, please refer to Van Wijk et al.