## Please Choose A Calculator

## 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.

- where:
- 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.