To obtain the desired measurement of , it is not sufficient to just measure .
The temperature at the reference junctions  must be already known.
Two strategies are often used here:
* "Ice bath" method: The reference junction block is immersed in a semi-frozen bath of distilled water at atmospheric pressure. The precise temperature of the melting point phase transition acts as a natural thermostat, fixing  to 0 °C. 
* Reference junction sensor (known as ""): The reference junction block is allowed to vary in temperature, but the temperature is measured at this block using a separate temperature sensor. This secondary measurement is used to compensate for temperature variation at the junction block. The thermocouple junction is often exposed to extreme environments, while the reference junction is often mounted near the instrument's location.  Semiconductor thermometer devices are often used in modern thermocouple instruments.
In both cases the value  is calculated, then the function  is searched for a matching value. The argument where this match occurs is the value of :