What is this tool?

The Multi-Material RTD Calculator is a free tool from Thermo Electric designed to convert resistance values to temperature readings (and vice versa) for a wide variety of industrial sensors, including Platinum (Pt100, Pt1000), Nickel (Ni120), and Copper (Cu10).

Unlike basic estimators that rely on simple linear approximations, this tool employs the full International Temperature Scale of 1990 (ITS-90) standards. It utilizes the complex Callendar-Van Dusen equation for platinum and specific high-order polynomials for nickel, ensuring mathematical accuracy across the entire spectrum, even in critical sub-zero ranges down to -200°C.

Built for process engineers, instrumentation technicians, and calibration specialists, this tool acts as an instant diagnostic aid in the field or lab. By eliminating the need for manual interpolation of printed Z-tables, it saves time and reduces human error. Users can input a multimeter reading to determine if a sensor is drifting or broken, with immediate feedback on standard tolerance limits (Class A, B, etc.) for platinum sensors. Whether verifying a cryogenic freezer or a high-heat furnace, this tool provides the confidence that your instrumentation data matches the physical reality of your process.

How to use it:

1. Choose your conversion: Switch between Temp → Res (to simulate a sensor) or Res → Temp (to interpret a reading).
2. Select your Sensor Type:
   • Platinum (Pt): Choose “IEC” for standard applications (α=0.00385) or “US” for legacy systems (α=0.00392).
   • Nickel (Ni) / Copper (Cu): Select these for specialized sensors (Ni120 or Cu10).
3. Check R0 (Nominal Resistance): The tool automatically suggests the standard value (e.g., 100Ω for Pt, 120Ω for Ni), but you can adjust this manually (e.g., set to 1000 for a Pt1000 sensor).
4. Set the Class (Pt Only): If using Platinum, select the Sensor Class (AA, A, B, or C) to see the specific pass/fail tolerance limits.
5. Get the result: Enter your temperature or resistance value to see the precise conversion and a real-time graph of the curve.

Why use this calculator?

• No more interpolation: Printed Z-tables only provide whole numbers. This tool calculates the exact value for decimals (e.g., 100.45°C) instantly using full polynomial equations.
• Instant Calibration Check: For Platinum sensors, the tool displays the official “Valid Range” based on the selected Class. If your reading falls outside these numbers, you know immediately that the sensor is out of spec.
• Multi-Material Support: Unlike standard tables that are often limited to Pt100, this tool handles the specific non-linear curves of Nickel (Ni120) and the linear response of Copper (Cu10) windings, making it a universal tool for diverse industrial environments.

Click here for more information on our RTD Temperature Sensors.