Difference between RTD and Thermocouple

Definition: Resistance temperature detectors (RTDs) and thermocouples are the most common types of sensors used to measure temperature. These are preferred over others for adjustment because they avoid cumbersome conversion procedures and are easily accessible for adjustment.

Difference between RTD and Thermocouple

The main difference between RTDs and thermocouples is their operation and construction. The notation shown below gives the difference between an RTD and a thermocouple.


RTD, which stands for Resistance Temperature Detectors, is a common type of sensor used to measure temperature. Similar to RTD, thermocouple is also widely used for thermal range measurement.

These two types of sensors were chosen for their ease of use compared to other measurement methods. In addition, these avoid cumbersome conversion procedures when dealing with temperature measurements.

However, there are differences between RTDs and thermocouples that are important to understand. This article highlights the key differences between RTDs and thermocouples.


A thermocouple is a sensing device consisting of two parallel conductors. The conductors used produced a voltage proportional to the temperature difference between the ends of the conductors.

Compared to other temperature sensors, thermocouples do not require an external form of stimulation because they are self-powered. Thermocouples measure the unknown temperature of a body relative to the known temperature of another body. RTDs and thermocouples are easy to use and help achieve faster results.

Difference between RTD and Thermocouple

RTD Thermocouple
RTD is more suited to measure lower ranges of temperature. The measuring range of an RTD lies between -200°C to 500 °C. A thermocouple can measure a larger range of temperatures. The measuring range lies between −180 °C to 2,320 °C.
RTD exhibits very good stability with low amounts of shifts Thermocouples have poor stability with results less repeatable over time.
RTD is more accurate than a thermocouple. Thermocouples have poor accuracy.
RTD is very sensitive and can register small changes in temperature. Thermocouples have poor sensitivity, which means that a small change in temperature is not recognised by it.
RTD has a good response time. The reaction time of a thermocouple is faster than that of an RTD.
The output presented by an RTD is linear. The output of a thermocouple is non-linear.
RTDs are more expensive than thermocouples. A thermocouple is cheaper than an RTD.


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