# Psychrometry Chart vs PE Prep Pro

The clearest difference is price: Psychrometry Chart at $1.99 against PE Prep Pro's $34.99. Psychrometry Chart also leads on update cadence (every 2 weeks vs every 4 weeks). On review sentiment, ads, in-app purchases and monetization model there is nothing between them.

Psychrometry Chart costs $1.99 and PE Prep Pro $34.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Psychrometry Chart ships an update every 2 weeks, PE Prep Pro every 4 weeks. The most recent releases landed on October 20, 2026 and October 19, 2026 respectively.

## The numbers

| Metric | Psychrometry Chart | PE Prep Pro |
| --- | --- | --- |
| Price | **$1.99** | $34.99 |
| Rating | — | **[2.0 (2 ratings)](https://appshunter.io/ios/app/pe-prep-pro/id6746470072/reviews)** |
| Number of ratings | — | **2** |
| Positive reviews | 0.0% of reviews | 0.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 2 weeks** | Every 4 weeks |
| Monetization | Paid | Paid |
| Size | 3 MB | 31 MB |
| Requires iOS | 15.6 | **15.1** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | +4 |
| Developer | [Konstantinos Ladiellis](https://appshunter.io/developer/1516103440) | [Examp, LLC](https://appshunter.io/developer/1479303574) |

## What reviewers say

### Psychrometry Chart

[App page](https://appshunter.io/ios/app/psychrometry-chart/id1516103441)

This app calculates and displays thermodynamic properties of moist air mixtures. It supports both SI and imperial units, allowing users to find values like dry-bulb temperature, relative humidity, and enthalpy by interacting with a chart. It also computes thermal comfort parameters.

**Highlights:** Moist air property calculation, SI and imperial unit support, Interactive chart with reticle, Displays dry-bulb temp, humidity, enthalpy, Calculates PMV/PPD thermal comfort

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

**In-app purchases:** none


### PE Prep Pro

[App page](https://appshunter.io/ios/app/pe-prep-pro/id6746470072)

This comprehensive exam preparation system offers over 1,400 realistic practice questions across 16 engineering disciplines. It provides detailed performance analytics to pinpoint weak areas and includes essential code summaries for offline study.

**Highlights:** 1,400+ realistic exam questions, 16 major engineering disciplines, Performance analytics, Offline functionality, Essential code summaries

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

**In-app purchases:** none


## Frequently asked questions

### Is Psychrometry Chart free?

Psychrometry Chart costs $1.99, with no in-app purchases.

### Is PE Prep Pro free?

PE Prep Pro costs $34.99, with no in-app purchases.

### Do Psychrometry Chart or PE Prep Pro have ads?

Neither Psychrometry Chart nor PE Prep Pro shows ads.

### Which is updated more often, Psychrometry Chart or PE Prep Pro?

Psychrometry Chart ships an update every 2 weeks, and PE Prep Pro every 4 weeks. Most recently, Psychrometry Chart was updated on October 20, 2026 and PE Prep Pro on October 19, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*