The “alpha” coefficient in RTD sensors, typically denoted as α, represents the rate of change of resistance with temperature. It defines how much the resistance of the RTD changes per degree Celsius and is crucial for determining the sensor’s accuracy. The most common value for platinum RTDs, like Pt100, is 0.00385 Ω/Ω/°C (shortened to 385 in calculator), based on the ITS-90 standard. This coefficient ensures that RTDs provide consistent and precise temperature readings across their operational range. Variations in alpha indicate different RTD standards and affect the sensor’s calibration.