All Hakko soldering stations are "factory adjusted" to meet the requirements of the soldering station specification. The stations also meet the the requirements of IPC J-STD-001 for Benchtop and Hand Soldering Systems. For tip temperature the accuracy requirement is +/- 15ºC (27ºF) of the selected temperature at idle. Calibration implies a paperwork trail with documentation to national standards. While the station meets the temperature requirements we do not provide paperwork/certificates of calibration with the station. Calibration (with documentation) can be ordered with the station for an additional fee. Hakko recommends a station be re-calibrated if the heating element is replaced.