Signals and sensors

Pt100 and Pt1000 resistance–temperature calculator

Convert between resistance and temperature on the IEC Pt-385 curve and show sensitivity plus the selected tolerance-class limit.

Calculate

RTD curve
°C
Ω
Confirm that the selected class is valid for the sensor construction and temperature range.
Construction changes the temperature range over which a tolerance class applies.

Worked example

Pt100 resistance

138.51 Ω

Temperature on the Pt-385 curve
100 °C
Curve sensitivity at this temperature
 Ω/°C
Class B tolerance
Not applicable
Class validity range for the construction
Construction not specified

With the construction unknown, the class validity range and tolerance are not reported. Lead resistance, self-heating, transmitter and acquisition uncertainty are excluded.

Underlined figures are rounded. Select one to copy its full value.

Method and assumptions

Formula

R(t) = R₀[1 + At + Bt² + C(t − 100)t³] below 0 °C; C = 0 at and above 0 °C

Pt-385 coefficients: A = 3.9083×10⁻³, B = −5.775×10⁻⁷ and C = −4.183×10⁻¹². Resistance-to-temperature conversion numerically inverts the same monotonic curve.

Limits of this result

  • AA, A, B and C here are complete resistance-thermometer tolerance classes, not F/W sensing-resistor class aliases and not total system uncertainty.
  • Lead resistance, self-heating, transmitter accuracy and the selected thermometer construction’s validity range require separate checks.

Technical sources

  1. IEC 60751:2022 — Industrial platinum resistance thermometers and sensorsIEC · Edition 3.0, 2022-01-27
  2. Pt100 Calculator — Pt-385 equation and coefficientsFluke · IEC 60751:2008 curve; accessed 2026-09-14
  3. Pt100 class B or F 0.3 — thermometer and sensing-resistor class distinctionsWIKA · accessed 2026-09-14
  4. Resistance thermometer tolerance valuesWIKA · document 3132465.01

Put the value to work

Read the related engineering guidance, or carry this task into System Builder to identify the signal path and EpiSensor products.

Continue in System Builder Read: Sensor Data in IoT: Collection, Quality and Use

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