Comparison

HVAC Formulator vs HVAC Pipe Sizer

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 Pipe Sizer

Quickly size low-pressure gas piping systems by inputting flow, pressure drop, diameter, or velocity. Includes detailed gas and pipe properties, fitting data, and unit conversion.

Highlights
  • Low pressure gas pipe sizing
  • Input flow, pressure drop, diameter, or velocity
  • Calculate exact and nominal pipe diameters
  • Specify gas and pipe properties
  • Includes pipe fitting equivalent lengths
  • English and metric unit display
Features
Read full description

The "HVAC Pipe Sizer - Gas Low" application allows you to quickly size a simple low pressure (less than 1.5psi) gas piping system by inputting a number of piping and gas properties. You can specify the total gas flow in cuft/hr (CubicM/hr) and one of either pressure drop (in. wg or Pa), pipe internal diameter (inches) or gas velocity (ft/s) parameters. The results include both the exact and nominal pipe diameters and the calculated velocity and total pipe equivalent length. If you are analyzing an existing pipe system, there is an option to input the existing pipe internal diameter and one of either pressure drop or gas velocity parameters to derive the calculated gas flow and other remaining properties. You can specify additional parameters such as the type of gas, various properties of the gas, the pipe material type, the total length of pipe, quantities for up to 11 different types of pipe fittings, and much more. You can also choose to display values in either english or metric units. This application includes built-in pipe fitting equivalent length and nominal pipe sizing tables for a wide variety of pipe material types and diameters. The "HVAC Pipe Sizer - Gas Low" application uses slider controls that allow you to quickly increment or decrement the input values and immediately observe the calculated results. You can also manually input exact values. All values can be displayed in English (IP) and Metric (SI) units. This application was designed by Carmel Software Corporation, a leader in HVAC design software since 1995. In fact, Autodesk (the makers of AutoCAD) acquired our load calculation software and incorporated it into their leading 3D modeling software called Revit. We also offer the following additional applications for the iPhone/iPad: 1. HVAC Duct Sizer 2. HVAC Pipe Sizer – Gas Low Pressure 3. HVAC Pipe Sizer - Gas High Pressure 4. HVAC Pipe Sizer – Liquid 5. HVAC Pipe Sizer – Steam 6. Steam Tables 7. Psychrometric Plus 8. Psychrometric LT 9. HVAC Pipe Sizer Plus 10. HVAC Pipe Sizer Gas Plus 11. HVAC Toolkit 12. HVAC Toolkit Ultimate 13. HVAC Residential Load Calcs 14. HVAC Load Plus 15. HVAC Equipment Locator 16. ASHRAE Duct Fitting Database 17. ASHRAE 62.1 Ventilation Load Calcs 18. HVAC Psych HD 19. HVAC ResLoad-J 20. HVAC Residential Load Calcs HD

Screenshots

HVAC Formulator4 screens
HVAC Pipe Sizer4 screens

Verdict

The call

The clearest difference is review sentiment: HVAC Pipe Sizer at 100% against HVAC Formulator's 9%. HVAC Pipe Sizer also leads on rating (5.0 vs 2.0) and in-app purchases (none vs 1). HVAC Formulator's advantage is update cadence (every 2 months vs every 9 months). On price, ratings volume, ads and monetization model 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 Pipe Sizer $4.99 up front. HVAC Formulator sells 1 one-off in-app purchase. HVAC Pipe Sizer asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

HVAC Pipe Sizer holds the better App Store score, 5.0 against 2.0. Both are backed by a comparable volume of ratings — 1 and 2 respectively. Written reviews point the same way: 9% of HVAC Formulator's written reviews are positive against 100% of HVAC Pipe Sizer's.

UpkeepUpdate frequency

HVAC Formulator ships an update every 2 months, HVAC Pipe Sizer every 9 months. The most recent releases landed on October 31, 2026 and November 1, 2026 respectively.

Scorecard4 real differences · 6 level
HVAC Formulator versus HVAC Pipe Sizer: the parameters behind the verdict, then further details
ParameterHVAC FormulatorHVAC Pipe Sizer
Price$4.99$4.99
Rating2.0 (1 ratings)5.0 (2 ratings) — better
Positive reviews9.1% of reviews100.0% of reviews — better
Number of ratings12 — better
Update frequencyEvery 2 months — betterEvery 9 months
AdsNoNo
In-app purchasesYesNo — better
MonetizationPaidPaid
DevicesiPhone, iPadiPhone, iPad
Requires iOS18.617.0 — better
Further details — not scored
Size73 MB1 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 Pipe Sizer

All ratings2 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews2 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

1 purchases

HVAC Formulator

One-time1
  • HVAC Pro$3.99
None

HVAC Pipe Sizer

No in-app purchases

Questions

Is HVAC Formulator free?
HVAC Formulator costs $4.99, and also offers in-app purchases.
Is HVAC Pipe Sizer free?
HVAC Pipe Sizer costs $4.99, with no in-app purchases.
Which has better reviews, HVAC Formulator or HVAC Pipe Sizer?
HVAC Pipe Sizer is rated higher. HVAC Formulator averages 2.0 out of 5 from 1 ratings, while HVAC Pipe Sizer averages 5.0 from 2 ratings.
Do HVAC Formulator or HVAC Pipe Sizer have ads?
Neither HVAC Formulator nor HVAC Pipe Sizer shows ads.
Which is updated more often, HVAC Formulator or HVAC Pipe Sizer?
HVAC Formulator ships an update every 2 months, and HVAC Pipe Sizer every 9 months. Most recently, HVAC Formulator was updated on October 31, 2026 and HVAC Pipe Sizer on November 1, 2026.

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