# Lambda Tuner vs Flow Rate Help

The clearest difference is rating: Flow Rate Help at 4.3 against Lambda Tuner's 3.3. Flow Rate Help also leads on ratings volume (44 vs 3) and price ($0.99 vs $3.99). On update cadence, ads, in-app purchases and monetization model there is nothing between them.

Lambda Tuner costs $3.99 and Flow Rate Help $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Flow Rate Help holds the better App Store score, 4.3 against 3.3. That said, the two scores are not equally well evidenced: Flow Rate Help has 44 ratings behind it against 3, so its average is the more settled of the two.

Lambda Tuner ships an update every 19 months, Flow Rate Help every 15 months. The most recent releases landed on July 5, 2026 and August 6, 2026 respectively.

## The numbers

| Metric | Lambda Tuner | Flow Rate Help |
| --- | --- | --- |
| Price | $3.99 | **$0.99** |
| Rating | [3.3 (3 ratings)](https://appshunter.io/ios/app/lambda-tuner/id632731065/reviews) | **[4.3 (44 ratings)](https://appshunter.io/ios/app/flow-rate-help/id1009898806/reviews)** |
| Number of ratings | 3 | **44** |
| Positive reviews | — | 0.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 19 months | **Every 15 months** |
| Monetization | Paid | Paid |
| Size | 1 MB | 3 MB |
| Requires iOS | 16.6 | **11.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod, Mac** |
| Age rating | 4+ | 4+ |
| Developer | [Johan Bjors](https://appshunter.io/developer/632731068) | [Armchair Engineering](https://appshunter.io/developer/398901339) |

## What reviewers say

### Lambda Tuner

[App page](https://appshunter.io/ios/app/lambda-tuner/id632731065)

This tool helps tune PID controllers using the Lambda method to calculate P, I, and D parameters. It's designed for intuitive use in various process industries and works on self-regulating and integrating loops. You can also use it to learn the impact of different PID parameters.

**Highlights:** Lambda method for PID parameter calculation, Supports self-regulating and integrating loops, Intuitive and easy to use interface, Adjustable Lambda value for reaction speed, Manual PID parameter testing, Educational tool for PID parameter impact

**Features:** macOS Compatibility

**In-app purchases:** none


### Flow Rate Help

[App page](https://appshunter.io/ios/app/flow-rate-help/id1009898806)

Calculate liquid flow rate, pipe diameter, or velocity with ease. Customize units for diameter, velocity, and flow rate, and set your preferred decimal places for precise results.

**Highlights:** Solve flow rate equations, Customizable diameter units, Customizable velocity units, Customizable flow rate units, Set decimal places

**Features:** Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Lambda Tuner free?

Lambda Tuner costs $3.99, with no in-app purchases.

### Is Flow Rate Help free?

Flow Rate Help costs $0.99, with no in-app purchases.

### Which has better reviews, Lambda Tuner or Flow Rate Help?

Flow Rate Help is rated higher. Lambda Tuner averages 3.3 out of 5 from 3 ratings, while Flow Rate Help averages 4.3 from 44 ratings.

### Do Lambda Tuner or Flow Rate Help have ads?

Neither Lambda Tuner nor Flow Rate Help shows ads.

### Which is updated more often, Lambda Tuner or Flow Rate Help?

Lambda Tuner ships an update every 19 months, and Flow Rate Help every 15 months. Most recently, Lambda Tuner was updated on July 5, 2026 and Flow Rate Help on August 6, 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.*