# AirDiffuser vs Fomcal

The clearest difference is in-app purchases: AirDiffuser at none against Fomcal's 1. AirDiffuser also leads on iOS requirement (9.0 vs 12.0). Fomcal's advantage is update cadence (every 3 months vs every 60 months) and price ($1.99 vs $2.99). On ads and device support there is nothing between them.

AirDiffuser costs $2.99 and Fomcal $1.99 up front. Fomcal sells 1 one-off in-app purchase. AirDiffuser asks for nothing beyond the download.

AirDiffuser ships an update every 60 months, Fomcal every 3 months. Both last shipped on September 28, 2026.

## The numbers

| Metric | AirDiffuser | Fomcal |
| --- | --- | --- |
| Price | $2.99 | **$1.99** |
| Rating | **[1.0 (1 ratings)](https://appshunter.io/ios/app/airdiffuser/id441746795/reviews)** | — |
| Number of ratings | **1** | — |
| Positive reviews | — | 75.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 60 months | **Every 3 months** |
| Monetization | Paid | **Free with in-app purchases** |
| Size | 4 MB | 6 MB |
| Requires iOS | **9.0** | 12.0 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Technical Data Service Co.,Ltd.](https://appshunter.io/developer/441746798) | [NOBORU IMAI](https://appshunter.io/developer/896071356) |

## What reviewers say

### AirDiffuser

[App page](https://appshunter.io/ios/app/airdiffuser/id441746795)

Quickly select air ceiling diffusers for HVAC systems. Input wind amount to calculate apparatus size and wind velocity. Supports various diffuser types and customizable settings for site and meeting use.

**Highlights:** Easy apparatus size selection by wind amount input, Supports various diffuser types (Round, Square, BL, CL, etc.), Adjustable aperture rate and wind velocity, Reverse calculation of wind amount, Metric system calculations, Calculations for BL and CL round length

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


### Fomcal

[App page](https://appshunter.io/ios/app/fomcal/id954145664)

This app allows you to create and save custom calculation formulas for daily use. It supports complex functions, logical operations, and parameter studies, with options to export results as CSV. An optional numeric pad enhances input efficiency.

**Highlights:** Save and reuse custom formulas, Support for logical and comparison functions, Parameter study for variable analysis, Export results as CSV, Optional enhanced numeric pad, Extended syntax for branching and iteration

**Features:** Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Enhancements | $1.99 | one-time |


## Frequently asked questions

### Is AirDiffuser free?

AirDiffuser costs $2.99, with no in-app purchases.

### Is Fomcal free?

Fomcal costs $1.99, and also offers in-app purchases.

### Do AirDiffuser or Fomcal have ads?

Neither AirDiffuser nor Fomcal shows ads.

### Which is updated more often, AirDiffuser or Fomcal?

AirDiffuser ships an update every 60 months, and Fomcal every 3 months. Most recently, AirDiffuser was updated on September 28, 2026 and Fomcal on September 28, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*