Comparison

HVAC Psychrometric Plus vs DB50X

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

HVAC Psychrometric Plus

Perform single-state and mixed-air psychrometric calculations quickly and easily. Select input parameters and view updated results on a single screen. Supports 23 input combinations and offers email/spreadsheet export.

Highlights
  • Single-state psychrometric calculations
  • Mixed-air psychrometric calculations
  • 23 input parameter combinations
  • Real-time result updates
  • Universal app for iPhone and iPad
  • Email and spreadsheet export
Features
Read full description

The "HVAC Psychrometric Plus" app is the #1 selling psychrometric application for the Apple iPhone and iPad. Thousands of happy users have downloaded this useful application for performing quick and simple psychrometric analysis. Just a few reasons why you should buy this application: 1. The Psych Plus is a universal app that it is optimized for the iPhone and iPad. 2. This app was developed by Carmel Software, a company that has been developing software for 25+ years. We are experts in software design and HVAC analysis. 3. It allows you to easily perform single-state and mixed-air HVAC psychrometric calculations. 4. Select and update all input parameters and view the calculated results all in the same screen without switching from one screen to another. 5. Select from 23 different combinations of any 2 input parameters such as "Humidity Ratio / Dewpoint Temperature" and much more. 6. Immediately view updated results as you change the input values using the on-screen slider control. You can specify how much to increase or decrease values as you slide the indicator along the slider mechanism. 7. Send an HTML email and a spreadsheet attachment of all of the single-state and mixed-air inputs and results This application contains two separate input modes. The 1st input mode is the "Single-State" mode that allows you to specify 2 psychrometric parameters for a single stream of air and view the remaining 6 calculated values. You can quickly toggle through 23 different combinations of the 2 input parameters and instantly view the calculated results, all on the same screen. The 2nd input mode is the "Mixed-Air" mode that allows you to specify 2 psychrometric parameters for each of two air streams to calculate the mixed air psychrometric conditions. Once again, you can toggle through 23 combinations of the 2 input parameters and view all results in one screen. The following input and output value-types are displayed: 1. Dry-bulb temperature 2. Humidity ratio 3. Relative Humidity 4. Wet-bulb temperature 5. Partial pressure 6. Enthalpy 7. Specific volume 8. Dewpoint temperature 9. Total airflow or mass flow (for mixed-air calcs, only) You can specify additional parameters such as the altitude of the air being analyzed, the atmospheric pressure, different types of units such as degrees F or R, and English or Metric units. The "HVAC Psychrometric Plus" application was designed by Carmel Software Corporation, a leader in HVAC design software since 1995. In fact, Autodesk (the makers of AutoCAD) acquired our analysis software and incorporated it into their leading Autodesk Revit software product. In addition, ASHRAE has hired Carmel Software to develop custom mobile apps to accompany their various standards. We also offer the following apps for the iPhone/iPad: 1. HVAC Residential Load Calcs 2. HVAC Load Plus 3. HVAC Duct Sizer 4. HVAC Pipe Sizer – Gas Low Pressure 5. HVAC Pipe Sizer - Gas High Pressure 6. HVAC Pipe Sizer – Liquid 7. HVAC Pipe Sizer – Steam 8. Steam Tables 9. HVAC Toolkit 10. Psychrometric LT 11. HVAC Pipe Sizer Plus 12. HVAC Pipe Sizer Gas Plus 13. HVAC Quick Load 14. HVAC ResLoad-J 15. HVAC Equipment Locator 16. HVAC Psych HD

About

DB50X

This scientific calculator offers high-precision computations with arbitrary precision for numbers. It supports advanced functions like complex numbers, matrices, symbolic calculations, and graphing, with a user-friendly interface and extensive built-in help.

Highlights
  • Arbitrary precision calculations
  • RPN and algebraic operations
  • Complex numbers, vectors, matrices
  • Symbolic and numerical solving
  • Graphing and plotting
  • Engineering units and constants
  • Unicode text support
Features
Read full description

DB50X is a new high-precision scientific calculator inspired by the legendary HP50G series from Hewlett-Packard. It is not an emulator, but a redesign from scratch, which is faster, and delivers never seen before capabilities like computations in arbitrary precision. Like the original HP50G, DB48X supports an unlimited stack, RPN and algebraic operations, complex numbers, based numbers, vectors, matrices, text, symbolic computations, numerical solving and integration, graphing and plotting, statistics, engineering units, and well over 1000 built-in functions. It integrates a library of equations and constants covering mathematics, physics or chemistry. Using modern technologies, DB50X goes well beyond the original HP50G in many ways: - It is significantly faster, uses less memory, and features a higher-resolution 240x400 pixels graphical color display. - Integer and decimal values can have an arbitrarily large number of digits, so you can compute log(pi) with 200 digits in a few keystrokes. - The six function keys feature up to three function per key, giving quick access to up to 18 related functions at a time. - Complex numbers can mix and match polar and rectangular form. - Symbolic operations extend to complex numbers, vectors and matrices. - Based numbers can be in any base from 2 to 36, and support any number of bits, making it easy to emulate a 23-bit or 512-bit processor. - Text is represented using Unicode instead of the proprietary HP encoding, facilitating data exchange with the rest of the world. - Multiple graphs can be distinguished using colour patterns - Engineering units include all the modern evolutions of the SI system, and can be configured by the user, e.g. to integrate currency units with the exchange rate du jour. Converting between USD/hour and EUR/day has never been so easy! - A built-in hyperlinked help system documents functions simply by holding the corresponding key, and combine a quick start guide, a user manual and a reference manual. - Over 700K of memory is available for RPL programs. - Access to iCloud to save your program and edit them from your Mac. DB508X will run many user RPL programs designed for the HP48, HP49 or HP50 directly as is. However, since it is not an emulator, it will not run any HP binary object, and notably will not run HP50G games or anything involving system RPL. This is an early-access release. Please consult https://github.com/c3d/db48x/blob/stable/doc/5-Unimplemented.md for a list of commands that are not yet implemented. DB50X is part of a family of related calculators that include the black-and-white DB48X and the entry-level DB40X.

Screenshots

HVAC Psychrometric Plus4 screens
DB50X4 screens

Verdict

The call

The clearest difference is rating: DB50X at 5.0 against HVAC Psychrometric Plus's 3.0. DB50X also leads on in-app purchases (none vs 1) and update cadence (every 3 weeks vs every 6 months). HVAC Psychrometric Plus's advantage is price ($6.99 vs $9.99). On ads, monetization model and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

HVAC Psychrometric Plus costs $6.99 and DB50X $9.99 up front. HVAC Psychrometric Plus sells 1 one-off in-app purchase. DB50X asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

DB50X holds the better App Store score, 5.0 against 3.0. Both are backed by a comparable volume of ratings — 2 and 9 respectively. Written reviews point the same way: 73% of HVAC Psychrometric Plus's written reviews are positive against 100% of DB50X's.

UpkeepUpdate frequency

HVAC Psychrometric Plus ships an update every 6 months, DB50X every 3 weeks. The most recent releases landed on October 29, 2026 and October 30, 2026 respectively.

Scorecard7 real differences · 3 level
HVAC Psychrometric Plus versus DB50X: the parameters behind the verdict, then further details
ParameterHVAC Psychrometric PlusDB50X
Price$6.99 — better$9.99
Rating3.0 (2 ratings)5.0 (9 ratings) — better
Positive reviews72.7% of reviews100.0% of reviews — better
Number of ratings29 — better
Update frequencyEvery 6 monthsEvery 3 weeks — better
AdsNoNo
In-app purchasesYesNo — better
MonetizationPaidPaid
DevicesiPhone, iPadiPhone, iPad, iPod — better
Requires iOS17.014.0 — better
Further details — not scored
Size1 MB7 MB
Age rating+44+
DeveloperCarmel Software CorporationChristophe de Dinechin

Customer experience

HVAC Psychrometric Plus

All ratings2 ratings
Positive50.0%
Neutral0.0%
Negative50.0%
Written reviews11 reviews
Positive72.7%
Neutral0.0%
Negative27.3%

DB50X

All ratings8 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews5 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

1 purchases

HVAC Psychrometric Plus

One-time1
  • HVAC Equipment Locator$9.99
None

DB50X

No in-app purchases

Questions

Is HVAC Psychrometric Plus free?
HVAC Psychrometric Plus costs $6.99, and also offers in-app purchases.
Is DB50X free?
DB50X costs $9.99, with no in-app purchases.
Which has better reviews, HVAC Psychrometric Plus or DB50X?
DB50X is rated higher. HVAC Psychrometric Plus averages 3.0 out of 5 from 2 ratings, while DB50X averages 5.0 from 9 ratings.
Do HVAC Psychrometric Plus or DB50X have ads?
Neither HVAC Psychrometric Plus nor DB50X shows ads.
Which is updated more often, HVAC Psychrometric Plus or DB50X?
HVAC Psychrometric Plus ships an update every 6 months, and DB50X every 3 weeks. Most recently, HVAC Psychrometric Plus was updated on October 29, 2026 and DB50X on October 30, 2026.

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