Thermistor R/T Calculators

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Calculators for Temperature and Thermistor Applications

Beta Value Calculator - The approximate relationship between the resistance and temperature for a NTC thermistor.

Defense R – T (Resistance vs. Temperature Tables) – M23648 and M32192 Defense Ratios for defense and aerospace applications use slightly different values than QTI’s standard curves. MIL-PRF and NSAS/GSFC parts always use MIL-spec curves.

R – T (Resistance vs. Temperature Tables) – A table showing the standard resistance at each temperature point.

Steinhart-Hart Calculator - The Steinhart–Hart equation is a model of the resistance of a semiconductor at different temperatures.
Steinhart Equation
  • T is the temperature (in Kelvin)
  • R is the resistance at T (in ohms)
  • A, B, and C are the Steinhart-Hart coefficients which vary depending on the type and model of thermistor and the temperature range of interest. (The most general form of the applied equation contains a (ln(R))2 term, but this is frequently neglected because it is typically much smaller than the other coefficients, and is therefore not shown above.)

Basic Thermistor Formulas
To find degree tolerance – Add standard part tolerance to maximum deviation and divide by the NTC value.
To find percent tolerance – Multiply degree tolerance by NTC value.