# Plumbing Formulator vs Psychro Chart

The clearest difference is in-app purchases: Psychro Chart at none against Plumbing Formulator's 4. Psychro Chart also leads on rating (4.8 vs 4.6) and iOS requirement (7.0 vs 18.6). Plumbing Formulator's advantage is update cadence (every 2 months vs every 9 months) and review sentiment (9% vs 0%). On price, ratings volume, ads and monetization model there is nothing between them.

Both are free to download. Plumbing Formulator sells 4 one-off in-app purchases. Psychro Chart asks for nothing beyond the download.

Psychro Chart holds the better App Store score, 4.8 against 4.6. Both are backed by a comparable volume of ratings — 7 and 6 respectively. Written reviews complicate that: 9% of Plumbing Formulator's written reviews are positive against 0% of Psychro Chart's, so the app with the better star average is not the one people write more warmly about.

Plumbing Formulator ships an update every 2 months, Psychro Chart every 9 months. The most recent releases landed on October 30, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | Plumbing Formulator | Psychro Chart |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.6 (7 ratings)](https://appshunter.io/ios/app/plumbing-formulator/id303497783/reviews) | **[4.8 (6 ratings)](https://appshunter.io/ios/app/psychro-chart/id1072047219/reviews)** |
| Number of ratings | **7** | 6 |
| Positive reviews | **9.1% of reviews** | 0.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 2 months** | Every 9 months |
| Monetization | Free | Free |
| Size | 123 MB | 27 MB |
| Requires iOS | 18.6 | **7.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Historycentral.com](https://appshunter.io/developer/1744330560) | [Condair GmbH](https://appshunter.io/developer/903871077) |

## What reviewers say

### Plumbing Formulator

[App page](https://appshunter.io/ios/app/plumbing-formulator/id303497783)

This professional calculator app provides over 200 formulas, calculators, and reference materials for plumbers, HVAC technicians, and mechanical contractors. It covers a wide range of calculations for water flow, piping, drainage, water heaters, pumps, and more, all in one pocket-sized tool.

**Highlights:** Over 200 formulas and calculators, Water flow and supply calculations, Pipe and piping calculations, Drainage and venting calculations, Water heater and pump calculations, Reference charts and code books, Pipe cut list optimizer

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

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Pro Version | $1.99 | one-time |
| Pro Purchase | $3.99 | one-time |
| Starter | $5.99 | one-time |
| Growth | $9.99 | one-time |


### Psychro Chart

[App page](https://appshunter.io/ios/app/psychro-chart/id1072047219)

This app simplifies complex air humidity calculations for humidification and heating needs. It allows for quick and accurate assessment of various scenarios using psychrometric or Mollier diagrams.

**Highlights:** Calculate air conditions, Determine humidification/heating needs, Perform psychrometric calculations, Use Mollier diagrams, Assess scenarios quickly

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Plumbing Formulator free?

Plumbing Formulator is free to download, with in-app purchases available.

### Is Psychro Chart free?

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

### Which has better reviews, Plumbing Formulator or Psychro Chart?

Psychro Chart is rated higher. Plumbing Formulator averages 4.6 out of 5 from 7 ratings, while Psychro Chart averages 4.8 from 6 ratings.

### Do Plumbing Formulator or Psychro Chart have ads?

Neither Plumbing Formulator nor Psychro Chart shows ads.

### Which is updated more often, Plumbing Formulator or Psychro Chart?

Plumbing Formulator ships an update every 2 months, and Psychro Chart every 9 months. Most recently, Plumbing Formulator was updated on October 30, 2026 and Psychro Chart on October 24, 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.*