#Convert voltage to temperature formula how to#

The calibration equation uses a ratio of two smaller order polynomials rather than one large order polynomial. The rational polynomial coefficients provided here produce an order of magnitude lower errors than the NIST ITS-90 type J thermocouple coefficients for direct and inverse polynomials.Ī rational polynomial function approximation for Type J thermocouples is used for computing temperature from measured thermocouple potential.

#Convert voltage to temperature formula how to#

This page shows you how to convert Type J thermocouple voltage to temperature with rational polynomial functions more efficiently and more accurately than you can using higher order polynomials. However, high order polynomials are often not very accurate – they produce systematic errors as the polynomial oscillates around the fitted data, as shown in these curve fits to Type K thermocouple data.īut there is a better way – using the ratio of two lower order polynomial functions.

The National Institute of Standards and Technology ( NIST database of thermocouple values) shows a high order polynomial formula with coefficients curve fitted to Type J thermocouple data they also provide.

If you use Mosaic's Thermocouple Wildcard, Type J thermocouple voltage measurements are converted to temperatures for you by the Wildcard's software drivers, and at high accuracy.īut for those of you not using it, but looking for accurate equations for thermocouple voltage to temperature conversion, we hope these thermocouple calibration coefficients are helpful.Įquations for voltage/temperature conversion usually are based on high-order polynomials.