Resistance of Pt100 temperature sensors

Pt100 temperature sensors

The name Pt100 is composed of the chemical symbol for platinum (Pt) and the resistance value of 100 ohms specified at 0°C.
The Pt100 sensor is based on the principle that the electrical resistance of an electrical conductor changes with a change in changes in temperature.
So actually almost all electrically conductive materials can be used.
For practical use in temperature measurement, however, they must meet certain conditions. In practice, in addition to nickel (Ni100), copper (Cu10) and silicon, the use of platinum as a resistive element has mainly proved successful.
Platinum has a high melting temperature and high chemical resistance, which allows precise measurements, with high stability and accuracy, even under adverse conditions.

PTC temperature sensors

Like all metals, the Pt100 sensor has a temperature-dependent resistance that increases with rising temperature. (PTC = Positive Temperature Coefficient). A useful change in resistance already occurs at low temperatures.

NTC temperature sensors

In addition to metal temperature sensors, sensors made of a wide variety of metal oxides are also used in mass applications. These often provide a usable change in resistance only at higher temperatures.
The resistance decreases when the temperature increases (NTC = Negative Temperature Coefficient).
The advantage of these sensors is the low-cost production and the small design with high response sensitivity.
On the other hand, the lower accuracy, the restricted measuring span, sensor-specific resistance values and a non-linear change in resistance, which make an adaptation of the downstream evaluation electronics necessary.

Pt100 Resistance - Resistance values according to DIN EN 60751

The Pt100 resistance is a standardized platinum temperature sensor according to DIN EN 60751 with a nominal resistance of 100 ohms at 0 °C.
The temperature-dependent resistance follows a precisely defined characteristic curve and is determined using standardized calculation formulas.
Depending on the temperature range from −200 °C to +850 °C, different formulas with the constants A, B, and C are used to calculate precise and reproducible resistance values in ohms.
With our Pt100 calculator, you can calculate the exact Pt100 resistance in ohms for any temperature.

Please enter a temperature value in °C and press the "Calculate" button.
The right window then displays the resistance in ohms calculated for the Pt100 resistance sensor.

Calculation formulas for Pt100 resistor acc. DIN EN 60751

The Pt100 resistance is calculated in accordance with DIN EN 60751 using different formulas depending on the temperature range.

• Temperature range: -200 to 0°C:
  R_t = R₀ * (1 + A * t + B * t² + C * (t-100) * t³)
• Temperature range: 0 to 850°C:
  R_t = R₀ * (1 + A * t + B * t²)

R_t=Resistance [Ohm] at desired temperature
R₀=Nominal resistance Pt100 at 0°C = 100 Ohm
t= desired temperature [°C]
A= 3,9083 * 10^-3
B= -5,775 * 10^-7
C= -4,183 * 10^-12

Please note:
The constant "A" for spectrally pure platinum is 3,925*10^-3.
As the production of spectrally pure platinum was complex and therefore expensive, the constant "A" was defined as the value for platinum contaminated with other substances.
A further advantage of "defined impurity" platinum is that it is less sensitive to additional external impurities, making the sensor more stable over the long term.
The value of 3,9083 * 10^-3 specified in DIN EN IEC 60751:2023-06 is used as the usual value for constant "A".
For high-precision measurements or when recalibrating a Pt temperature sensor, it is important to know which platinum the sensor was made of and which value of constant "A" is used to calculate the temperature.
Especially with older Pt temperature sensors or with Pt sensors manufactured in non-European countries, different platinum based on other standards (DIN 43760-1980, ASTME, JIS, Gost, etc.) is sometimes used. There may be deviations from the values specified in DIN EN IEC 60751:2023-06.

Create Pt100 tables – resistance table calculator