We present a time-dependent numerical laser model, which is affirmed by experimental results of two different pulsed alexandrite laser regimes. The model can help to better understand the experimental findings and to determine the possible limitations of these systems. For this, the relevant temperature-dependent alexandrite transitions are incorporated, and measured data is included to generate almost the same conditions as in the laboratory. A comparison was made between the simulated and experimental results in terms of output energy, pulse duration and temporal shape, as well as laser wavelength in two different setups, a Q-switched and a cavity-dumped Q-switched system. The simulation replicated the experiment’s findings numerically, which could be demonstrated for the first time for pulsed alexandrite lasers. Additionally, the limits of the cavity-dumped Q-switched setup with respect to the shortest possible pulse length could be investigated using the numerical model.