Difference Between a Thermistor and an RTD

What is the difference between a thermistor and an RTD and how do they work?

What are RTDs and Thermistors?

Thermistors and RTDs (resistance temperature detectors) are both types of temperature sensors that measure temperature by measuring electrical resistance. They are both widely used for temperature measurement in various industries and applications.

Differences between Thermistors and RTDs

There are several differences between Thermistors and RTDs, these differences make them more suitable for different applications.

Construction Material

The main difference between thermistors and RTDs is the material they are made of. Thermistors are typically composed of mixed metal oxides, while RTDs are made of pure metal such as nickel or platinum. The material difference leads to different properties in temperature measurement. Thermistors are more accurate than RTDs, even in the wiring of the associated devices.

Wire Length

Thermistors have higher resistance values at lower temperatures which gives them higher resolution. Because the wire increases resistance, using very long wires can alter the reading and can cause inaccuracies. Because they have high inherent resistances, thermistors can be used with very long wire strands, while RTDs are only recommended up to 3m without further measures. This can make a difference when selecting which temperature is best for your application depending on the required wire length.

Temperature Range

A thermistor is better for lower temperatures whereas RTDs are more suitable for higher temperatures. Thermistors can only be used in a temperature range up to 250°C, while RTDs can be used up to 600°C.

Type of Application

Thermistors are typically used in more commonplace devices such as freezers, air conditioners or water heaters. This is because of their high resolution in lower temperature ranges. Because of this, thermistors are also well suited for use in medical devices. RTOn the other hand, RTDs e mainly used in industrial applications where higher temperatures can occur.

Summary

To summarise, the differences between thermistors and RTDs are;

-Thermistors are made of metal oxide mixtures while RTDs are made of pure metals

-Thermistors have equal or better accuracy than RTDs

-Thermistors allow longer cable lengths compared to RTDs

-RTDs provide better stability

-RTDs have a wider temperature range than thermistors

-RTDs are mostly used in the industrial field, while thermistors are more used for everyday use

Thermistors and RTDs from Variohm

We have a wide range of temperature sensors available. These can be seen on our website.

Thermistors

RTD Sensors

You can also find out more about temperature sensors by downloading our Temperature Sensors Overview.

and find out more about our range of different types of temperature sensors by taking a look at our Infographic.