This work presents a critical temperature study of La 1−x Ca x MnO 3 manganites in bulk by means of Monte Carlo method thermal activated magnetic properties. The analysis was carried out for stoichiometries in the range of 0≤x≤1. The model is based on a three-dimensional classical Heisenberg–Hamiltonian involving the presence of Mn 3+eg , Mn 3+eg′ and Mn 4+ ions, and their nearest neighbor interaction. For this modeling, simple cubic lattice samples of size L 3 , with L=6, 15 and 30 were used. The values of exchange parameters were determined by using LaMnO 3 (x=0), La 0.5 Ca 0.5 MnO 3 and CaMnO 3 (x=1) phases. Relationships between exchange parameters and anisotropy constants for different hole densities were found. Results of transition temperatures for each phase showed good agreement with experimental reports, especially for L=30 and L→∞.