# Fan Law Calculator

> HVAC fan law calculator for system performance estimation. (iPhone/iPad app by Pheinex, LLC.)

- Source: https://appshunter.io/ios/app/fan-law-calculator/id1114006510 (this page in markdown: same URL + `.md`)
- Developer: [Pheinex, LLC](https://appshunter.io/developer/996932317)
- Category: Productivity, Business
- Price: $9.99
- Rating: 5.00/5 from 4 App Store ratings · 1 written reviews indexed
- Age rating: 4+
- Requires: iOS 13.0 · 0 MB
- Languages: American English
- Released: 2016-05-24
- Data updated: 2026-08-25
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/fan-law-calculator/id1114006510/reviews.md

## What is Fan Law Calculator?

The Fan Law Calculator App has been designed to allow quick estimation of the performance impact of variation in airflow and/or rpm on an existing system. The standard fan law equations are used to estimate the system performance changes.

Input the current values for airflow, rpm, pressure and current (or power) into the appropriate text field. The calculations will automatically update as you type.

The updated values can be input in one of two ways. The new values can be entered into the appropriate text field. Or, you can drag the airflow value left and right on the graph view to change the values. The calculations will automatically update as you edit the values.

Calculations

The standard fan law equations are applied:
cfm2 = cfm1 * rpm2/rpm1
sp2 = sp1 * (cfm2/cfm1)^2
power2 = power1 * (cfm2/cfm1)^3

Notes:
This application (App) is provided for use by qualified HVAC engineers and designers in the design of air handling systems and is not a substitute for appropriate design services. When in doubt, contact a design

## Key features

- Estimate airflow and RPM impact
- Uses standard fan law equations
- Automatic calculation updates
- Graph view for value adjustment
- Input current airflow, RPM, pressure, and current/power

## Chart rankings

- #195 in Top Paid · Productivity (US App Store)

## Recent user reviews (1 of 1)

All indexed reviews: https://appshunter.io/ios/app/fan-law-calculator/id1114006510/reviews.md

### 5/5 — Sr. Application Engineer

*2026-07-10*

Works great

## Frequently asked questions about Fan Law Calculator

### What is Fan Law Calculator used for?

Fan Law Calculator is used to quickly estimate the performance impact of variations in airflow and/or RPM on an existing HVAC system, utilizing standard fan law equations.

### How does Fan Law Calculator calculate performance changes?

It applies standard fan law equations such as cfm2 = cfm1 * rpm2/rpm1, sp2 = sp1 * (cfm2/cfm1)^2, and power2 = power1 * (cfm2/cfm1)^3 to estimate system performance changes.

### Can I adjust values visually in Fan Law Calculator?

Yes, you can input updated values by typing them into the appropriate fields or by dragging the airflow value left and right on the graph view, with calculations updating automatically.

### What devices is Fan Law Calculator available on?

Fan Law Calculator is available on iPhone, iPad, and iPod.

### What is the price of Fan Law Calculator?

Fan Law Calculator is a paid app priced at $9.99.

### How often is Fan Law Calculator updated?

The app was last updated on February 9, 2024, with the latest version being 1.2.

### Is Fan Law Calculator suitable for beginners?

The app is provided for use by qualified HVAC engineers and designers and is not a substitute for appropriate design services. If in doubt, contact a design professional.

### Does Fan Law Calculator have ads?

No, Fan Law Calculator does not contain advertisements.

## Version history (last 5 releases)

### 1.2 — 2024-02-09

Bug fixes and improvements.

### 1.1 — 2019-09-25

• iOS 13 updates
• Dark mode

### 1.0.3 — 2016-09-23

Found and fixed another iOS 10 crasher.

### 1.0.2 — 2016-09-20

- Updated for iOS 10
- Fixed startup crasher in iOS 10

### 1.0.1 — 2016-05-27

Fixed app store URL in "Please Rate Fan Law Calculator".
Other minor improvements.

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## More apps by Pheinex, LLC

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- [Pipe Sizer - Water](https://appshunter.io/ios/app/pipe-sizer-water/id1316033381)

All apps by Pheinex, LLC: https://appshunter.io/developer/996932317

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*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 2026-08-25.*