# Scientific Calculator Plus 991 vs iDynamics

The clearest difference is review sentiment: Scientific Calculator Plus 991 at 92% against iDynamics's 0%. Scientific Calculator Plus 991 also leads on update cadence (fortnightly vs every 3 months). iDynamics's advantage is in-app purchases (none vs 4) and ads (none vs shown). On price and device support there is nothing between them.

Both are free to download. Scientific Calculator Plus 991 sells 4 in-app purchases, starting at $1.99 per month. iDynamics asks for nothing beyond the download.

Scientific Calculator Plus 991 ships an update fortnightly, iDynamics every 3 months. The most recent releases landed on November 5, 2026 and November 3, 2026 respectively.

## The numbers

| Metric | Scientific Calculator Plus 991 | iDynamics |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.7 (13K ratings)](https://appshunter.io/ios/app/scientific-calculator-plus-991/id1449106995/reviews)** | — |
| Number of ratings | **13K** | — |
| Positive reviews | **91.7% of reviews** | 0.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | **Fortnightly** | Every 3 months |
| Monetization | Free with in-app purchases | **Free** |
| Size | 169 MB | 10 MB |
| Requires iOS | 15 | **12.0** |
| Devices | **iPhone, iPad, iPod, Mac** | iPhone, iPad, iPod |
| Age rating | 12+ | 4+ |
| Developer | [Tran Duy](https://appshunter.io/developer/1449106994) | [proCampus GmbH](https://appshunter.io/developer/1513150595) |

## What reviewers say

### Scientific Calculator Plus 991

[App page](https://appshunter.io/ios/app/scientific-calculator-plus-991/id1449106995)

This app is a powerful scientific calculator with graphing capabilities, a formula library, and a unit converter. It offers natural display input, advanced math functions for algebra, calculus, and statistics, and supports various number bases and formats.

**Highlights:** Natural display input, Graphing module, Formula library, Unit and currency converter, Algebra and calculus tools, Matrix and vector operations, Statistical calculations

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

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Calculator month subscription | $1.99 | per month |
| Calculator yearly subscription | $3.99 | per year |
| Calculator Premium | $5.99 | one-time |
| Calculator Pro | $5.99 | one-time |

**What reviewers like**

- 👍 Intuitive and easy to use
- 🚀 Powerful and feature-rich
- 💡 Customizable interface and settings
- 🔍 Extensive library of formulas and equations
- ⚙️ Handles complex math and scientific functions well

**What reviewers complain about**

- 🐛 Occasional bugs and input issues
- 🔀 Confusing layout and button placement
- 💰 Some advanced features locked behind paywall

**Reported bugs**

- Keyboard input stops working after switching screens
- Incorrect calculation results for certain operations
- App crashes on some devices after recent update

**Requested features**

- Add option to change display font and color
- Improve cursor control and editing capabilities
- Implement auto-simplification for complex expressions
- Add more handwriting font options
- Expand graphing and equation solving features


### iDynamics

[App page](https://appshunter.io/ios/app/idynamics/id1513150926)

This app facilitates learning and teaching by enabling vibration and shock measurements for system identification and structural health monitoring. It helps detect and evaluate changes in a structure's dynamic properties, such as those caused by damage.

**Highlights:** Vibration and shock measurements, System identification analysis, Frequency and damping determination, Structural health monitoring, Damage detection and evaluation, Educational purposes

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Scientific Calculator Plus 991 free?

Scientific Calculator Plus 991 is free to download, with in-app purchases available.

### Is iDynamics free?

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

### Do Scientific Calculator Plus 991 or iDynamics have ads?

Scientific Calculator Plus 991 shows ads; iDynamics does not.

### Which is updated more often, Scientific Calculator Plus 991 or iDynamics?

Scientific Calculator Plus 991 ships an update fortnightly, and iDynamics every 3 months. Most recently, Scientific Calculator Plus 991 was updated on November 5, 2026 and iDynamics on November 3, 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.*