AC magnetic susceptibility of La1−xCaxMnO3 (x = 0.25, 0.33, 04, 0.5) thin films was obtained using Monte Carlo simulations combined with Fourier transform. The material stoichiometry was varied depending on the combination of Mn 4+ and Mn 3+ ions. Hamiltonian used includes the Heisenberg interaction, magnetocrystalline anisotropy, and Zeeman effect. For determining AC susceptibility, a time-dependent external magnetic field h(t) was applied. The study was conducted for various angular frequencies and temperatures. The simulations were obtained using a graphical interface that allowed the online monitoring of the results. According to the results, the AC susceptibility decreases not only with the temperature but also with the frequency.