# Orifice Flow Rate Calculator vs LWF Observer

The clearest difference is update cadence: LWF Observer at weekly against Orifice Flow Rate Calculator's every 6 months. LWF Observer also leads on iOS requirement (13.0 vs 15.6). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Orifice Flow Rate Calculator ships an update every 6 months, LWF Observer weekly. The most recent releases landed on October 24, 2026 and October 17, 2026 respectively.

## The numbers

| Metric | Orifice Flow Rate Calculator | LWF Observer |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.9 (113 ratings)](https://appshunter.io/ios/app/orifice-flow-rate-calculator/id1439701941/reviews)** | — |
| Number of ratings | **113** | — |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 6 months | **Weekly** |
| Monetization | Free | — |
| Size | 2 MB | 35 MB |
| Requires iOS | 15.6 | **13.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [R.L. Laughlin & Company, Inc.](https://appshunter.io/developer/1438670681) | [LWF TECHNOLOGIES LTD](https://appshunter.io/developer/1713708772) |

## What reviewers say

### Orifice Flow Rate Calculator

[App page](https://appshunter.io/ios/app/orifice-flow-rate-calculator/id1439701941)

Easily calculate natural gas orifice flow rates using the AGA 3 standard. This utility app allows users to determine MCF production for a given duration, save calculations, and export data to CSV. It functions offline, requiring no cell service.

**Highlights:** Orifice MCF Calculator, Rotary (Direct) MCF Calculator, Save all calculations, View saved inputs and calculations, Export calculations to CSV

**Features:** macOS Compatibility

**In-app purchases:** none


### LWF Observer

[App page](https://appshunter.io/ios/app/lwf-observer/id6470452164)

**In-app purchases:** none


## Frequently asked questions

### Is Orifice Flow Rate Calculator free?

Orifice Flow Rate Calculator is free to download, with no in-app purchases.

### Is LWF Observer free?

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

### Do Orifice Flow Rate Calculator or LWF Observer have ads?

Neither Orifice Flow Rate Calculator nor LWF Observer shows ads.

### Which is updated more often, Orifice Flow Rate Calculator or LWF Observer?

Orifice Flow Rate Calculator ships an update every 6 months, and LWF Observer weekly. Most recently, Orifice Flow Rate Calculator was updated on October 24, 2026 and LWF Observer on October 17, 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.*