# P-T Calculator > HVAC/R pressure and temperature calculation tool with automatic altitude correction. (iPhone/iPad app by National Refrigerants Inc..) - Source: https://appshunter.io/ios/app/p-t-calculator/id1252176525 (this page in markdown: same URL + `.md`) - Developer: [National Refrigerants Inc.](https://appshunter.io/developer/1252176524) - Category: Reference, Utilities - Price: Free - Rating: 4.80/5 from 52 App Store ratings · 9 written reviews indexed - Age rating: 4+ - Requires: iOS 15.6 · 6 MB - Languages: American English - Released: 2018-01-04 - Data updated: 2026-08-26 - Monetization: free - User reviews in markdown: https://appshunter.io/ios/app/p-t-calculator/id1252176525/reviews.md ## What is P? This comprehensive Pressure/Temperature calculation tool from National Refrigerants provides several unique features designed to make the HVAC/R technician’s job easier. This 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. For refrigerant blends, both saturated vapor and saturated liquid values are displayed. Within the superheat/subcool screen, a graphic display for blends will show the entering, mid-point, and outlet temperature as well as line temperature. Other features include: - Automatic altitude correction (if location services are enabled) - English/Metric units - Easily choose from “favorites” refrigerants list - Supplementary information about refrigerants and links to NRI website - Link to NRI Lubricant Cross Reference app - Link to NRI Branch Locator tool ## Key features - Pressure/Temperature calculation - Superheat/Subcool calculation - Automatic altitude correction - English/Metric units - Favorite refrigerants list - Refrigerant blend data ## Recent user reviews (9 of 9) All indexed reviews: https://appshunter.io/ios/app/p-t-calculator/id1252176525/reviews.md ### 4/5 — Good App needs R454B support *2023-03-22* Good handy application, needs to add R-454B support in list of refrigerants. ### 5/5 — Best P-T app available *2021-05-12* Makes life easy when working on HVACR systems! ### 5/5 — Easy to use! *2020-05-03* The gauges I bought have saturated temps in Celsius while everything else I have is in Fahrenheit! This app made the process super easy as well as automating the simple math to calculate Subcool/Superheat values. ### 5/5 — Tiny *2018-05-02* Best PT chart out there!!! Really helpful with my daily work load. ### 5/5 — Great app! *2018-05-01* Great app! ### 5/5 — Great Tool *2018-05-01* Great tool with many features most P-T apps don’t have. Helps show glide and calculates superheat / subcooling and many other helpful things. ### 5/5 — Best app for blend refrigerants *2018-05-01* Have used this app a few times servicing new high glide refrigerant systems and it works great. It compensates for changes in glide temperatures which is very helpful for new refrigerants ### 5/5 — Best P-T app! *2018-05-01* Best P-T app! Easy to understand, great graphics to understand glide ### 5/5 — PT Chart *2018-05-01* Simply the best out there. Just download it already thank me later. ## Frequently asked questions about P ### What is P-T Calculator used for? P-T Calculator is a tool for HVAC/R technicians to calculate pressure/temperature relationships, superheat, and subcool. It can also display saturated vapor and liquid values for refrigerant blends. ### Does P-T Calculator work offline? The description does not specify offline functionality. However, features like automatic altitude correction suggest it may utilize location services, which typically require an internet connection. ### What refrigerants does P-T Calculator support? P-T Calculator allows users to easily choose from a favorites list of refrigerants. It also displays specific data for refrigerant blends, including saturated vapor and liquid values. ### How accurate is P-T Calculator? The app has a high rating of 4.8 stars from 51 ratings, indicating strong user satisfaction with its accuracy and functionality. ### Is P-T Calculator available on Android? P-T Calculator is currently supported on iPhone and iPad devices. The description does not mention Android compatibility. ### How often is P-T Calculator updated? The latest version, 1.25, was last updated on September 21, 2025. This indicates a relatively recent update, suggesting ongoing support and development. ### Does P-T Calculator have ads? No, P-T Calculator does not contain advertisements. It is a free application without any ad interruptions. ### What is the age rating for P-T Calculator? P-T Calculator has an age rating of 4+, making it suitable for a wide range of users. ## Version history (last 5 releases) ### 1.31 — 2026-08-21 Added more refrigerants. ### 1.25 — 2025-09-21 Added refrigerants ### 1.1 — 2024-02-02 Added new refrigerants and updated the altitude lookup. ### 1.0.7 — 2021-06-02 Calculation fix ### 1.0.6 — 2020-06-03 Added new refrigerants ## Apps similar to P | App | Rating | Price | Category | | --- | --- | --- | --- | | [HVACR Check & Charge](https://appshunter.io/ios/app/hvacr-check-and-charge/id574809181) | 4.8 (17,119) | Free | Reference | | [Copeland Mobile](https://appshunter.io/ios/app/copeland-mobile/id789715706) | 4.8 (5,160) | Free | Reference | | [Copeland PT Pro](https://appshunter.io/ios/app/copeland-pt-pro/id465298520) | 3.3 (7) | Free | Reference | ## Related topics [pressure temperature chart](https://appshunter.io/ios/topics/pressure-temperature-chart) · [chemours pt calc](https://appshunter.io/ios/topics/chemours-pt-calc) · [chemours](https://appshunter.io/ios/topics/chemours) · [bitzer refrigerant ruler](https://appshunter.io/ios/topics/bitzer-refrigerant-ruler) · [hvac pt chart](https://appshunter.io/ios/topics/hvac-pt-chart) · [pt chart](https://appshunter.io/ios/topics/pt-chart) · [pt chart refrigerants eu](https://appshunter.io/ios/topics/pt-chart-refrigerants-eu) · [ptpro](https://appshunter.io/ios/topics/ptpro) · [danfoss pt chart](https://appshunter.io/ios/topics/danfoss-pt-chart) · [elmec heaters](https://appshunter.io/ios/topics/elmec-heaters) · [pressure temperature](https://appshunter.io/ios/topics/pressure-temperature) · [supercool slide rule hvac](https://appshunter.io/ios/topics/supercool-slide-rule-hvac) · [johnstone supply hvacr](https://appshunter.io/ios/topics/johnstone-supply-hvacr) · [check charge](https://appshunter.io/ios/topics/check-charge) · [lftr](https://appshunter.io/ios/topics/lftr) · [honeywell pt chart](https://appshunter.io/ios/topics/honeywell-pt-chart) · [temperatura unit](https://appshunter.io/ios/topics/temperatura-unit) · [hvac check charge](https://appshunter.io/ios/topics/hvac-check-charge) · [refrigerant slider](https://appshunter.io/ios/topics/refrigerant-slider) · [lubricant change ledger2026](https://appshunter.io/ios/topics/lubricant-change-ledger2026) --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-26.*