# ASHRAE Psychrometric Chart vs testo Smart

The clearest difference is price: testo Smart at Free against ASHRAE Psychrometric Chart's $19.99. testo Smart also leads on update cadence (every 2 months vs every 11 months). ASHRAE Psychrometric Chart's advantage is in-app purchases (none vs 5) and review sentiment (27% vs 16%). On ads and device support there is nothing between them.

testo Smart is free to download; ASHRAE Psychrometric Chart costs $19.99 up front. testo Smart sells 5 in-app purchases, starting at $6.99 per month. ASHRAE Psychrometric Chart asks for nothing beyond the download.

ASHRAE Psychrometric Chart ships an update every 11 months, testo Smart every 2 months. The most recent releases landed on October 12, 2026 and October 29, 2026 respectively.

## The numbers

| Metric | ASHRAE Psychrometric Chart | testo Smart |
| --- | --- | --- |
| Price | $19.99 | **Free** |
| Rating | — | **[2.7 (170 ratings)](https://appshunter.io/ios/app/testo-smart/id1482139629/reviews)** |
| Number of ratings | — | **170** |
| Positive reviews | **27.3% of reviews** | 16.3% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 11 months | **Every 2 months** |
| Monetization | Paid | **Free with in-app purchases** |
| Size | 2 MB | 195 MB |
| Requires iOS | **13.0** | 18.0 |
| Devices | iPad | **iPhone, iPad** |
| Age rating | 4+ | 4+ |
| Developer | [ASHRAE, Inc.](https://appshunter.io/developer/375374912) | [Testo SE & Co. KGaA](https://appshunter.io/developer/966489178) |

## What reviewers say

### ASHRAE Psychrometric Chart

[App page](https://appshunter.io/ios/app/ashrae-psychrometric-chart/id584295008)

This interactive tool allows users to plot and customize psychrometric charts on their iPad. Easily create and save HVAC process graphs, update properties dynamically, and share charts and data via email. Supports both IP and SI units.

**Highlights:** Interactive psychrometric chart plotting, Customizable chart appearance, Dynamic property updates, Create and edit points and labels, Email charts and data, Unlimited projects and templates, Zoom and pinch functionality

**Features:** macOS Compatibility

**In-app purchases:** none


### testo Smart

[App page](https://appshunter.io/ios/app/testo-smart/id1482139629)

This app supports measurements for refrigeration, HVAC, and heating systems. It also aids in food safety, frying oil quality, and indoor climate monitoring. Quickly interpret data, create digital reports with photos, and send them via email.

**Highlights:** All-in-one system measurements, Graphical display of measured values, Digital PDF/CSV measurement reports, Email report sharing, Leak test analysis, Automatic refrigerant charging, Indoor air quality monitoring

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

**In-app purchases (5)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Multi-site measurement | $6.99 | per month |
| Air balancing | $9.99 | per month |
| Multi-site measurement | $69.90 | per year |
| Air balancing | $99.90 | per year |
| Logging digital manifold | $44.99 | one-time |

**What reviewers like**

- 👍 Good app with some features
- 🚀 Great product
- 🚀 Useful app for measurements

**What reviewers complain about**

- 🐛 App won't connect
- 🐛 Connectivity issues
- 🐛 Unreliable connection
- 🐛 Forced updates
- 🐛 Laggy and unresponsive UI

**Reported bugs**

- App won't connect to devices
- Compatibility issues with newer iOS versions
- Frequent crashes and freezes
- Inability to save favorite refrigerants
- Measurement data not displaying properly

**Requested features**

- Add option to toggle Bluetooth discovery
- Improve Bluetooth range
- Add ability to customize colors and graphs
- Improve data export functionality
- Add option to name sensors


## Frequently asked questions

### Is ASHRAE Psychrometric Chart free?

ASHRAE Psychrometric Chart costs $19.99, with no in-app purchases.

### Is testo Smart free?

testo Smart is free to download, with in-app purchases available.

### Do ASHRAE Psychrometric Chart or testo Smart have ads?

Neither ASHRAE Psychrometric Chart nor testo Smart shows ads.

### Which is updated more often, ASHRAE Psychrometric Chart or testo Smart?

ASHRAE Psychrometric Chart ships an update every 11 months, and testo Smart every 2 months. Most recently, ASHRAE Psychrometric Chart was updated on October 12, 2026 and testo Smart on October 29, 2026.

---

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