# HydroCalc Plus vs RiegoAppArg

The clearest difference is price: RiegoAppArg at Free against HydroCalc Plus's $3.99. RiegoAppArg also leads on in-app purchases (none vs 4) and update cadence (every 4 days vs every 3 weeks). On ads, device support and iOS requirement there is nothing between them.

RiegoAppArg is free to download; HydroCalc Plus costs $3.99 up front. HydroCalc Plus sells 4 one-off in-app purchases. RiegoAppArg asks for nothing beyond the download.

HydroCalc Plus ships an update every 3 weeks, RiegoAppArg every 4 days. The most recent releases landed on October 4, 2026 and October 2, 2026 respectively.

## The numbers

| Metric | HydroCalc Plus | RiegoAppArg |
| --- | --- | --- |
| Price | $3.99 | **Free** |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/hydrocalc-plus/id578807688/reviews)** | — |
| Number of ratings | **1** | — |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 3 weeks | **Every 4 days** |
| Monetization | Paid | — |
| Size | 34 MB | 61 MB |
| Requires iOS | 15.1 | 15.1 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Transparent Blue Water LLC](https://appshunter.io/developer/1847968351) | [Luciano Nico Acosta](https://appshunter.io/developer/1409909480) |

## What reviewers say

### HydroCalc Plus

[App page](https://appshunter.io/ios/app/hydrocalc-plus/id578807688)

A professional tool for hydraulic engineers to calculate pressure losses in piping systems. It supports US and SI units, offers an extensive pipe material and fittings database, and includes inverse calculations for design optimization.

**Highlights:** Friction head loss calculation (Hazen-Williams), US and SI unit support, Extensive pipe material library, Fittings and valves database, Inverse calculation mode, Real-time results (velocity, losses)

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

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Pump Power Calculator | $1.99 | one-time |
| System Curve Generator | $1.99 | one-time |
| Pipe Database | $1.99 | one-time |
| Industrial Fluids Pack | $2.99 | one-time |


### RiegoAppArg

[App page](https://appshunter.io/ios/app/riegoapparg/id6771389482)

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

**In-app purchases:** none


## Frequently asked questions

### Is HydroCalc Plus free?

HydroCalc Plus costs $3.99, and also offers in-app purchases.

### Is RiegoAppArg free?

RiegoAppArg is free to download, with no in-app purchases.

### Do HydroCalc Plus or RiegoAppArg have ads?

Neither HydroCalc Plus nor RiegoAppArg shows ads.

### Which is updated more often, HydroCalc Plus or RiegoAppArg?

HydroCalc Plus ships an update every 3 weeks, and RiegoAppArg every 4 days. Most recently, HydroCalc Plus was updated on October 4, 2026 and RiegoAppArg on October 2, 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.*