The invention relates to a thermal cycler (10) comprising a housing (12), the housing (12) accommodating a thermal block (14) having a plurality of sample wells (32), each for receiving a test sample in a sample vessel, electric heater means (18) for heating the thermal block (14), a power supply (24) and an electronic control (22) for controlling the electric heater means (18), and further comprising a temperature analysis and/or verification unit (28) for analyzing and/or verifying a thermal performance of the thermal block (14). The invention further relates to a method for analyzing or verifying a thermal performance of a thermal cycler (10) and for calibrating the thermal cycler (10). The thermal cycler (10) is characterized in that the temperature analysis and/or verification unit (28) is integrated into the housing (12) and is connected to the power supply (24) and to the electronic control (22) by means of an internal interface (26), whereas the method is characterized by the following steps: providing the thermal cycler (10) with an integrated temperature analysis and/or verification unit (28) and using the integrated temperature analysis and/or verification unit (28) for self-calibration of the thermal cycler (10).