# ExtCalc vs Charging Engine

The clearest difference is review sentiment: Charging Engine at 52% against ExtCalc's 0%. Charging Engine also leads on update cadence (every 6 weeks vs every 5 months) and iOS requirement (12.0 vs 18.7). ExtCalc's advantage is monetization model (free with in-app purchases vs subscription) and device support (6 vs 2). On price, ads and in-app purchases there is nothing between them.

Both are free to download. ExtCalc sells 2 in-app purchases, starting at $4.99 per year and Charging Engine sells 12 in-app purchases, starting at $3.99 per 7 days. Whichever you choose, the download price is not the number that matters.

ExtCalc ships an update every 5 months, Charging Engine every 6 weeks. The most recent releases landed on September 25, 2026 and October 14, 2026 respectively.

## The numbers

| Metric | ExtCalc | Charging Engine |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.8 (11K ratings)](https://appshunter.io/ios/app/charging-engine-4kwallpapers/id1602309907/reviews)** |
| Number of ratings | — | **11K** |
| Positive reviews | 0.0% of reviews | **51.6% of reviews** |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 5 months | **Every 6 weeks** |
| Monetization | **Free with in-app purchases** | Subscription |
| Size | 7 MB | 112 MB |
| Requires iOS | 18.7 | **12.0** |
| Devices | **iPhone, iPad, Mac, Apple TV, Apple Watch, Vision Pro** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Matthias Weber](https://appshunter.io/developer/386132193) | [Bluewolf Technology Limited](https://appshunter.io/developer/1477300424) |

## What reviewers say

### ExtCalc

[App page](https://appshunter.io/ios/app/extcalc/id386132190)

This scientific calculator offers a colorized text view for formulas, allowing for individual calculation sheets and easy memorization of results. It features a customizable constants pool, VAT calculator, and cloud synchronization for seamless use across devices. Accessibility and team collaboration are also emphasized.

**Highlights:** Colorized formula view, Individual calculation sheets, Memorize results, Customizable constants pool, VAT calculator, Cloud synchronization, Apple Watch app

**Features:** Family Sharing

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Yearly Subscription | $4.99 | per year |
| Printing | $0.99 | one-time |


### Charging Engine

[App page](https://appshunter.io/ios/app/charging-engine-4kwallpapers/id1602309907)

Enhance your phone's charging experience with dynamic, futuristic animations and live wallpapers. Visualize battery performance and enjoy regular content updates to keep your device looking fresh and engaging.

**Highlights:** Futuristic charging animations, High-definition dynamic screensavers, Dozens of 3D charging wallpapers, Live wallpaper collections, Battery performance monitor, Regular content updates

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

**In-app purchases (12)**

| Purchase | Price | Billing |
| --- | --- | --- |
| ChargingEngine Subscription | $3.99 | per 7 days |
| ChargingEngine Subscription | $3.99 | per 7 days |
| Weekly subscription | $4.99 | per 7 days |
| ChargingEngine Subscription | $19.99 | per month |
| ChargingEngine Subscription | $19.99 | per month |
| ChargingEngine Subscription | $19.99 | per month |
| ChargingEngine Subscription | $23.99 | per month |
| ChargingEngine Subscription | $23.99 | per month |
| ChargingEngine Subscription | $69.99 | per year |
| ChargingEngine Subscription | $69.99 | per year |
| ChargingEngine Subscription | $69.99 | per year |
| ChargingEngine lifetime | $69.99 | one-time |

**What reviewers like**

- 🚀 Charging animations are cool
- 👍 Variety of wallpaper options
- 💡 Customizable charging experience

**What reviewers complain about**

- 🔒 Requires subscription to access full features
- 🐛 Buggy and crashes frequently
- 🔋 Drains battery when app is open
- 💸 Misleading about free trial, charges immediately

**Reported bugs**

- Wallpapers don't work as advertised
- App only functions when kept open during charging
- Subscription cannot be easily canceled

**Requested features**

- Add search bar to find desired wallpapers
- Allow users to upload their own photos/videos
- Provide option to mute sound effects
- Make app fully free without subscription


## Frequently asked questions

### Is ExtCalc free?

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

### Is Charging Engine free?

Charging Engine is free to download, with in-app purchases available.

### Do ExtCalc or Charging Engine have ads?

Neither ExtCalc nor Charging Engine shows ads.

### Which is updated more often, ExtCalc or Charging Engine?

ExtCalc ships an update every 5 months, and Charging Engine every 6 weeks. Most recently, ExtCalc was updated on September 25, 2026 and Charging Engine on October 14, 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.*