# Unit Converter Calculator Pro vs Diffraction Grating Calculator

The clearest difference is price: Unit Converter Calculator Pro at Free against Diffraction Grating Calculator's $2.99. Unit Converter Calculator Pro also leads on update cadence (monthly vs every 29 months). Diffraction Grating Calculator's advantage is in-app purchases (none vs 4) and ads (none vs shown). On device support and iOS requirement there is nothing between them.

Unit Converter Calculator Pro is free to download; Diffraction Grating Calculator costs $2.99 up front. Unit Converter Calculator Pro sells 4 one-off in-app purchases. Diffraction Grating Calculator asks for nothing beyond the download.

Unit Converter Calculator Pro ships an update monthly, Diffraction Grating Calculator every 29 months. The most recent releases landed on October 13, 2026 and September 29, 2026 respectively.

## The numbers

| Metric | Unit Converter Calculator Pro | Diffraction Grating Calculator |
| --- | --- | --- |
| Price | **Free** | $2.99 |
| Rating | **[4.7 (977 ratings)](https://appshunter.io/ios/app/unit-converter-calculator-pro/id1343845631/reviews)** | — |
| Number of ratings | **977** | — |
| Positive reviews | 76.2% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | **Monthly** | Every 29 months |
| Monetization | Free with in-app purchases | — |
| Size | 37 MB | 1 MB |
| Requires iOS | 13.0 | 13 |
| Devices | **iPhone, iPad, iPod, Apple Watch** | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Rome Rock LLC](https://appshunter.io/developer/1190244007) | [Nitrio](https://appshunter.io/developer/321121189) |

## What reviewers say

### Unit Converter Calculator Pro

[App page](https://appshunter.io/ios/app/unit-converter-calculator-pro/id1343845631)

Easily convert between metric and imperial units for a wide range of measurements including area, speed, temperature, and weight. Supports scientific prefixes and offers a history of your conversions. No internet connection required.

**Highlights:** Metric to Imperial unit conversion, Imperial to Metric unit conversion, Area, speed, temperature, volume, weight conversions, Scientific prefixes support, Conversion history, Offline functionality

**Features:** macOS Compatibility, Apple Watch app, Vision Pro support

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Remove Ads & Unlock Themes | $2.99 | one-time |
| Remove Ads & Unlock Themes 1 | $4.99 | one-time |
| Remove Ads & Unlock Themes 2 | $6.99 | one-time |
| Remove Ads & Unlock Themes 3 | $9.99 | one-time |

**What reviewers like**

- 🚀 Easy & accurate
- 🚀 Excellent Tool
- 👍 Goog for social
- 👍 Excelente para mi trabajo
- 👍 Sencillez

**What reviewers complain about**

- 👎 Hard to use interface
- 👎 Lacks pressure units
- 👎 No reverse button
- 👎 Metric to imperial format not user-friendly

**Reported bugs**

- 🐛 Changing to something else

**Requested features**

- 💡 Favorite conversations
- 💡 Color-coded sections
- 💡 Money conversion


### Diffraction Grating Calculator

[App page](https://appshunter.io/ios/app/diffraction-grating-calculator/id1413088894)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Unit Converter Calculator Pro free?

Unit Converter Calculator Pro is free to download, with in-app purchases available.

### Is Diffraction Grating Calculator free?

Diffraction Grating Calculator costs $2.99, with no in-app purchases.

### Do Unit Converter Calculator Pro or Diffraction Grating Calculator have ads?

Unit Converter Calculator Pro shows ads; Diffraction Grating Calculator does not.

### Which is updated more often, Unit Converter Calculator Pro or Diffraction Grating Calculator?

Unit Converter Calculator Pro ships an update monthly, and Diffraction Grating Calculator every 29 months. Most recently, Unit Converter Calculator Pro was updated on October 13, 2026 and Diffraction Grating Calculator on September 29, 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.*