We present a simple calibration method for europium‐doped potassium halide dosimeters. The procedure is based on the self‐irradiation absorbed dose of potassium halide thermoluminescence dosimeters due to the natural content of the radionuclide40K in potassium halide crystals. In the small dose range of the order of 0.5 mGy, the precision of the proposed method is highly competitive with traditional calibration methods, without the need of artificial radiation sources and rather expensive and sophisticated measurement equipment. ©1995 American Institute of Physics.