AirDiffuser vs Fomcal
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
AirDiffuser
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.
- 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
Read full descriptionHide full description
'AirDiffuser' is an application program that can select air ceiling diffuser in air conditioning facilities quickly, and easily. It is an easy operation only of the choice of the apparatus to be examined from the list, the input of the amount of the wind, and doing the calculation button the tap. It is possible to calculate to examine the velocity of the wind to select the size of apparatus and to examine the amount of the wind. Please use it for the reference when air ceiling diffuser is selected when the blueprint and the working drawing, etc. are made. It is possible to take an active part by various scenes like the site and meeting, etc. [Feature] - The size of apparatus can be easily selected only by inputting the amount of the wind and pushing the calculation button. - It corresponds to various apparatuses. (Round Diffuser,Square Diffuser,BL,CL,VHS,HS,OAG,EAG,Smoke Damper) - The aperture rate of default can be changed to an arbitrary aperture rate. - The velocity of the wind of default can be changed to an arbitrary velocity of the wind. - The velocity of the wind can be examined by fixing by an arbitrary size of apparatus. - The amount of the wind can be reversely calculated by fixing an arbitrary size of apparatus and the velocity of the wind. - When size L is selected, BL and CL round length and are computable. - This application is calculated by metric system. - Please see the support site in detail.
Fomcal
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.
- 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
Read full descriptionHide full description
Fomcal is a calculator to calculate quickly with formula inputted already. Since you can register formulas used in daily routine by yourself, there is no need to search or to develop the dedicated calc app. Moreover, Fomcal can be also available as a general function calculator pad (option). Registered formula can be utilized as a function in the other formula or on the calcpad. And constants or variables can be used in these. Fomcal can show descriptions and a figure, about formulas and variables. In addition to the numeric functions such as trigonometric functions, you can also use the logical or comparison functions. By describing separated multiple of a formula with a semicolon';', you will be able to calculate these at the same time. Temporary variables are available in formula definition as followings. exp) x=1;x+2 result) 3 You can try a parameter study with specifying an initial value, a incrementation and a repeat number. The result can be exported as CSV data. Following formulas are preset as samples. ・Hypotenuse of Right Triangle - Geometry ・Cross-sectional Performance of Rectangle - Mechanics of materials ・Roots of quadratic equation - Mathematics ・Compound interest calculation - Business ・Number of years to become N times with compound interest calculation After purchase of "Enhancements (former Restriction Release)" with In-App purchase, you will be able to following functions. ・Export/import of formula data. ・A special numeric pad will be utilized for efficient inputting. ・Function calculator pad. ・Parameter study. From Ver.3.3, "Extended Syntax" feature is available. With $IF, $FOR, $WHILE or etc., branch or iterative operation is easily specified.
Screenshots
Verdict
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.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
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.
| Parameter | AirDiffuser | Fomcal |
|---|---|---|
| Price | $2.99 | $1.99 — better |
| Rating | 1.0 (1 ratings) — better | — |
| Positive reviews | — | 75.0% of reviews |
| Number of ratings | 1 — better | — |
| Update frequency | Every 60 months | Every 3 months — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Paid | Free with in-app purchases — better |
| Devices | iPhone, iPod | iPhone, iPad, iPod — better |
| Requires iOS | 9.0 — better | 12.0 |
| Further details — not scored | ||
| Size | 4 MB | 6 MB |
| Age rating | 4+ | 4+ |
| Developer | Technical Data Service Co.,Ltd. | NOBORU IMAI |
Customer experience
AirDiffuser
Fomcal
In-app purchases
AirDiffuser
No in-app purchases
Fomcal
- Enhancements$1.99









