Thermistor and RTD lookup

Convert resistance to temperature and back for 10K Type II and Type III NTC thermistors and Pt100 or Pt1000 RTDs.

What this means

Disconnect the sensor and read its resistance, then compare with the temperature you measure next to it. If the two disagree by more than a few degrees, check the curve type, wiring resistance and the controller input setting before replacing the sensor.

Formula used

  • NTC: 1/T = A + B × ln(R) + C × ln(R)³ (Steinhart-Hart, T in kelvin)
  • 10K Type II: A = 1.129241e-3, B = 2.341077e-4, C = 8.775468e-8
  • 10K Type III: A = 1.028444e-3, B = 2.392435e-4, C = 1.562216e-7
  • RTD (IEC 60751): R = R0 × (1 + A·t + B·t²), plus C·(t − 100)·t³ below 0°C
  • A = 3.9083e-3, B = −5.775e-7, C = −4.183e-12

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