P-T Calculator, developed by National Refrigerants, is a free Android app designed for HVAC/R technicians. It is a comprehensive pressure/temperature calculation tool that offers several unique features to make the technician's job easier. The app can calculate a simple pressure/temperature relationship or calculate superheat/subcool temperatures. The user can input pressure or temperature(s) on any screen, and the other values are automatically calculated and displayed. The app also provides both saturated vapor and saturated liquid values for refrigerant blends.

One of the unique features of this app is its ability to automatically correct altitude (if location services are enabled). The app also offers English/Metric units, and users can easily choose from a list of "favorites" refrigerants. P-T Calculator provides supplementary information about refrigerants and links to the NRI website. Furthermore, it offers links to the NRI Lubricant Cross Reference app and NRI Branch Locator tool.

P-T Calculator is an excellent tool for HVAC/R technicians who want a comprehensive and easy-to-use pressure/temperature calculation app. It offers a wide range of features that make it stand out from other PT charts. With its user-friendly interface and unique features, P-T Calculator is a must-have app for HVAC/R technicians.