# PIDTune vs GasUnits

The clearest difference is price: GasUnits at Free against PIDTune's $4.99. GasUnits also leads on update cadence (every 10 days vs every 4 months). On rating, ratings volume, ads and in-app purchases there is nothing between them.

GasUnits is free to download; PIDTune costs $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.

On the App Store both sit at effectively the same score — 5.0 for PIDTune against 5.0 for GasUnits. Both are backed by a comparable volume of ratings — 2 and 1 respectively.

PIDTune ships an update every 4 months, GasUnits every 10 days. The most recent releases landed on October 8, 2026 and October 7, 2026 respectively.

## The numbers

| Metric | PIDTune | GasUnits |
| --- | --- | --- |
| Price | $4.99 | **Free** |
| Rating | [5.0 (2 ratings)](https://appshunter.io/ios/app/pidtune/id1045174726/reviews) | [5.0 (1 ratings)](https://appshunter.io/ios/app/gasunits/id6762513689/reviews) |
| Number of ratings | **2** | 1 |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 4 months | **Every 10 days** |
| Monetization | Paid | **Free** |
| Size | 1 MB | 30 MB |
| Requires iOS | **15.0** | 15.1 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Richard H Street](https://appshunter.io/developer/954888336) | [Vivek Chandra](https://appshunter.io/developer/461237208) |

## What reviewers say

### PIDTune

[App page](https://appshunter.io/ios/app/pidtune/id1045174726)

This utility calculates PID tuning parameters using the IMC method for various process and controller types. It allows for direct input of process gain or variable changes, with adjustable tuning aggression via a slider.

**Highlights:** IMC method for PID tuning, Calculates Kc, Ti, Td, Supports FO, SO, and I process types, Handles Parallel and Series controller types, Adjustable tuning aggression slider, Input process gain or variable changes

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

**In-app purchases:** none


### GasUnits

[App page](https://appshunter.io/ios/app/gasunits/id6762513689)

This app simplifies complex natural gas and LNG unit conversions for industry professionals. It accurately converts over 90 volume, rate, and price units, offering precise results and composition-based estimates. Easily copy formatted results for reports and models.

**Highlights:** Converts 90+ gas volume, rate, and price units, Supports three standard gas heating values, Calculates barrels of oil equivalent, Provides composition-based estimates, Fast, intuitive, and error-proof design, Copy results for reports and models

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

**In-app purchases:** none


## Frequently asked questions

### Is PIDTune free?

PIDTune costs $4.99, with no in-app purchases.

### Is GasUnits free?

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

### Which has better reviews, PIDTune or GasUnits?

PIDTune and GasUnits are both rated 5.0 out of 5 on the App Store, from 2 and 1 ratings respectively.

### Do PIDTune or GasUnits have ads?

Neither PIDTune nor GasUnits shows ads.

### Which is updated more often, PIDTune or GasUnits?

PIDTune ships an update every 4 months, and GasUnits every 10 days. Most recently, PIDTune was updated on October 8, 2026 and GasUnits on October 7, 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.*