Comparison

HVAC Formulator vs HVAC Toolkit Ultimate

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

Head to head
About

HVAC Formulator

This app provides HVAC professionals with over 900 essential formulas and calculations for load calculations and system design. It supports both US and Metric units, offers instant switching, and includes 23 calculator categories and over 460 unit conversions. Designed for field use, it works offline and allows users to save and share results.

Highlights
  • Over 900 formulas and calculations
  • US & Metric unit support
  • 23 calculator categories
  • 460+ unit conversions
  • 8 temperature scales
  • Offline functionality
  • Save and share results
Features
Read full description

HVAC FORMULATOR is the essential tool for Heating, Ventilating, and Air Conditioning professionals. With over 900 formulas and calculations, it covers everything from basic load calculations to advanced system design — all in your pocket. US & METRIC SUPPORT — Switch instantly between US (Imperial) and Metric (SI) units. Results display in both systems so you always have the value you need. Input labels and conversions update automatically. 23 CALCULATOR CATEGORIES including: - Cooling Load — Sensible, latent, and total cooling calculations, tons, EER, COP, and sensible heat ratio - Fan Laws — Speed and diameter affinity laws for CFM, pressure, and horsepower - Duct Sizing — Velocity, round and rectangular sizing, equivalent diameter, aspect ratio - Ventilation Rate — ASHRAE 62.1 breathing zone, air changes per hour, exhaust fan sizing - Electrical — Ohm's Law, single and three-phase power, motor FLA, watts to BTU/h - Gas Laws — Boyle's, Charles's, Gay-Lussac's, Combined, and Ideal Gas Law - Psychrometrics — Bypass factor, mixed air temperature, percent outside air, dew point - Hydronic Formulas — Heat transfer, flow rate, pipe velocity, expansion tank, Cv coefficient - Boiler — Efficiency calculations, BTU output, heat absorption - Refrigeration — Tonnage output, compression ratio, mass flow rate, COP - Ductwork — Velocity, velocity pressure, total pressure, equivalent round - Airside — Sensible heat, latent heat, total heat (US and Metric) - Piping — Pipe area, weight, friction loss, expansion, Hazen-Williams, 70+ formulas - Steam — Condensate loads, fuel calculations, steam flow - Pump Laws — Break horsepower, suction head, pump affinity laws - Energy — Fuel values for oil, gas, coal, propane, ethanol, and more - Heating Design — Electric heating, baseboard, radiant ceiling, boiler capacity, hydronic snow melting - Heating Requirement — Insulation-based load calculations - Humidity — Specific humidity, relative humidity, sensible and latent heat - Loads — Temperature loads, heat gains from lights, equipment, and machines - Temperature — Mixed air, liquid mixing, final temperature calculations - Waterside System — Total heat, evaporator and condenser flow rates - Air Change Rate — Air changes per hour, air flow rate 460+ UNIT CONVERSIONS across 16 categories: Metric, Pressures, BTU, Linear, Square, Cubic, Liquid Measures, Weights, Flows, Power, Horsepower, Watts, Hydraulic, Ft-Lbs, Sand/Volume, and HVAC-specific conversions. 8 TEMPERATURE SCALES — Convert between Celsius, Fahrenheit, Kelvin, Rankine, Reaumur, Newton, Delisle, and Romer. BUILT FOR PROFESSIONALS: - Search across all 900+ formulas instantly - Mark favorites for quick access - Save calculation history with full breakdown - Share and export results - Clean, fast interface designed for field use - Works offline — no internet required HVAC FORMULATOR is a professional-grade tool built for HVAC technicians, engineers, contractors, and students. New formulas and features are added regularly.

About

HVAC Toolkit Ultimate

This comprehensive application offers a suite of tools for HVAC professionals, including load calculations, equipment tracking, refrigerant charts, duct and pipe sizing, and psychrometric analysis. It consolidates multiple functionalities into a single, powerful utility for field and office use.

Highlights
  • Residential load calculations
  • Equipment nameplate data tracking
  • Refrigerant pressure-temperature charts
  • Superheat and subcool calculations
  • Duct and pipe sizing analysis
  • Psychrometric calculations
  • Steam table property calculations
Features
Read full description

This may just be the only HVAC app you will ever need. The HVAC Toolkit Ultimate from Carmel Software is a universal app that works on both the iPhone and iPad. It is the essential app for anyone in the HVAC industry. It is a compilation of most of the individual iPhone and iPad applications offered by Carmel Software plus bonus software. If you bought each of these apps separately, it would cost more than 2 times what the price of this app is. It includes: 1. HVAC Residential Load Calc HD (iPad version) 1. HVAC Residential Load Calcs (iPhone version) 1. HVAC Equipment Locator 2. HVAC PT Chart 3. HVAC Refrigerant Charge 4. HVAC Duct Sizer 2. HVAC Quick Load 6. ASHRAE Ventilation Calcs (iPhone version) 7. Psychrometrics 8. Steam Tables 9. HVAC Pipe Sizer - Liquid 10. HVAC Pipe Sizer - Steam 11. HVAC Pipe Sizer - Gas Low 12. HVAC Pipe Sizer - Gas High The "HVAC Residential Load Calcs" module allows you to perform comprehensive HVAC block and room-by-room load calculations for small commercial and residential buildings. You can easily use this module out in the field by taking advantage of the simplicity and power of the iPhone or iPad, and then email results back to your office. The "HVAC Equipment Locator" module allows you to track, share, and customize your equipment nameplate and maintenance data. The version here includes the ability to customize your input screens (this is usually an in-app purchase on the free stand-alone version of Locator, but it is included here). The "HVAC PT Chart" module allows you to easily view the pressure-temperature properties of 100 refrigerants. Think of this app as a digital version of the paper PT charts that you may have carried around with you in the past. The "HVAC Refrigerant Charge" module allows you to perform superheat and subcool refrigerant charge calculations on-the-fly. This app includes pressure-temperature data for over 100 common refrigerants including azeotropic (bubble/dew) versions of refrigerants. The "HVAC Duct Sizer" module allows you to perform quick and simple duct sizing analysis. You can specify the total airflow in CFM (or L/s), the aspect ratio and one of either the velocity of air or the friction loss per 100 feet (30 meters). The results include both the exact and rounded height and width (or diameter) dimensions and the calculated velocity and friction loss. In addition, you can calculate for a range of duct sizes by specifying minimum and maximum friction loss and airflow values. The "HVAC Quick Load" module allows you to quickly calculate total heating and cooling loads for a wide variety of building types. The "Psychrometrics" module allows you to easily perform single-state and mixed-air HVAC psychrometric calculations for up to 23 different combinations of input parameters. The "Steam Tables" module allows you to calculate the properties of saturated or superheated steam by specifying 2 input properties. This module is also part of the "Pipe Sizer - Steam" module discussed below. The "ASHRAE Ventilation Calcs" module allows you to perform comprehensive minimum ventilation calculations for a wide variety of commercial buildings based upon ASHRAE Standard 62.11-2007 and 2010/2013 versions. The "HVAC Pipe Sizer - Liquid" module allows you to size a pipe run for many different types of liquids (or fluids), pipe material and fitting types. The "HVAC Pipe Sizer - Steam" module allows you to size a steam pipe run, and it also includes a bonus steam table calculator. The "HVAC Pipe Sizer - Gas Low and Gas High" modules allows you to quickly size a simple low (less than or equal to 1.5 psi) and high (greater than 1.5 psi) pressure gas piping system by inputting a number of piping and gas properties. All values can be displayed in English (IP) and Metric (SI) units. We also offer all of the above modules as individual apps, too.

Screenshots

HVAC Formulator4 screens
HVAC Toolkit Ultimate4 screens

Verdict

The call

The clearest difference is price: HVAC Formulator at $4.99 against HVAC Toolkit Ultimate's $59.99. HVAC Formulator also leads on update cadence (every 2 months vs every 6 months) and chart position (#197 vs unranked). HVAC Toolkit Ultimate's advantage is rating (3.0 vs 2.0) and in-app purchases (none vs 1). 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 Formulator costs $4.99 and HVAC Toolkit Ultimate $59.99 up front. HVAC Formulator sells 1 one-off in-app purchase. HVAC Toolkit Ultimate asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

HVAC Toolkit Ultimate holds the better App Store score, 3.0 against 2.0. Both are backed by a comparable volume of ratings — 1 and 4 respectively. Written reviews point the same way: 9% of HVAC Formulator's written reviews are positive against 40% of HVAC Toolkit Ultimate's.

UpkeepUpdate frequency

HVAC Formulator ships an update every 2 months, HVAC Toolkit Ultimate every 6 months. The most recent releases landed on September 5, 2026 and August 27, 2026 respectively.

Scorecard8 real differences · 3 level
HVAC Formulator versus HVAC Toolkit Ultimate: the parameters behind the verdict, then further details
ParameterHVAC FormulatorHVAC Toolkit Ultimate
Price$4.99 — better$59.99
Rating2.0 (1 ratings)3.0 (4 ratings) — better
Positive reviews9.1% of reviews40.0% of reviews — better
Number of ratings14 — better
Update frequencyEvery 2 months — betterEvery 6 months
AdsNoNo
In-app purchasesYesNo — better
MonetizationPaidPaid
Best chart rank#197 — better—
DevicesiPhone, iPadiPhone, iPad, iPod — better
Requires iOS18.613.0 — better
Further details — not scored
Size73 MB59 MB
Age rating4+4+
DeveloperHistorycentral.comCarmel Software Corporation

Customer experience

HVAC Formulator

All ratings1 ratings
Positive0.0%
Neutral0.0%
Negative100.0%
Written reviews11 reviews
Positive9.1%
Neutral18.2%
Negative72.7%

HVAC Toolkit Ultimate

All ratings4 ratings
Positive50.0%
Neutral0.0%
Negative50.0%
Written reviews15 reviews
Positive40.0%
Neutral6.7%
Negative53.3%

In-app purchases

1 purchases

HVAC Formulator

One-time1
  • HVAC Pro$3.99
None

HVAC Toolkit Ultimate

No in-app purchases

Questions

Is HVAC Formulator free?
HVAC Formulator costs $4.99, and also offers in-app purchases.
Is HVAC Toolkit Ultimate free?
HVAC Toolkit Ultimate costs $59.99, with no in-app purchases.
Which has better reviews, HVAC Formulator or HVAC Toolkit Ultimate?
HVAC Toolkit Ultimate is rated higher. HVAC Formulator averages 2.0 out of 5 from 1 ratings, while HVAC Toolkit Ultimate averages 3.0 from 4 ratings.
Do HVAC Formulator or HVAC Toolkit Ultimate have ads?
Neither HVAC Formulator nor HVAC Toolkit Ultimate shows ads.
Which is updated more often, HVAC Formulator or HVAC Toolkit Ultimate?
HVAC Formulator ships an update every 2 months, and HVAC Toolkit Ultimate every 6 months. Most recently, HVAC Formulator was updated on September 5, 2026 and HVAC Toolkit Ultimate on August 27, 2026.

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