The thermostat in the heater should be accurate to 0.2 degrees (+/-), but deviations can occur—for example, due to air currents in the room or if the heater is placed away from where one normally resides.
Most heaters with a digital display can be calibrated to compensate for this. Refer to the user manual specific to your heater for guidance. Wi-Fi heaters and the Wi-Fi Socket can be calibrated via settings in the Mill app.
However, heaters with a mechanical thermostat, as well as heaters manufactured before 2017, cannot be calibrated.