Program Limits and Accuracy

PsyCalc® uses industry standard calculations to determine psychrometric property values. Each time a change is made to the input values PsyCalc® recalculates psychrometric properties. The program uses calculation methods and equations that have been generally accepted by the HVAC industry and ASHRAE.


The limits set within the program are imposed due to inaccuracies in the calculation methods and/or practical limits of the technology and industry for which PsyCalc® was created. The current limits are:

Dry Bulb Temperature -60 to 1500ºF (-51 to 815.5ºC)

Dew Point Temperature -80 to 200ºF (-51 to 71.1ºC)

Altitude -500 to 65,000 Ft (-152 to 19,800 m) above sea level

Pressure .7 to 400 psia (5 to 2,757 kPa)

(Moisture content is directly limited by the dew point limit.)


There is no simple way to state the accuracy of the calculated values presented by PsyCalc® over the entire range of its operation. Suffice it to say that standard industry recognized equations have been used and every effort made to avoid errors due to rounding.

It is the users responsibility however to qualify the accuracy and its applicability to the work they do. PsyCalc® was written for use by the HVAC industry and it is the authors opinion that it provides adequate accuracy for this industry. Please review the Disclaimer for further information.

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