# Interactive Photosynthesis vs Equation Encyclopedia

The clearest difference is price: Equation Encyclopedia at Free against Interactive Photosynthesis's $1.99. Equation Encyclopedia also leads on update cadence (every 4 days vs every 25 months). Interactive Photosynthesis's advantage is in-app purchases (none vs 9) and ads (none vs shown). On device support there is nothing between them.

Equation Encyclopedia is free to download; Interactive Photosynthesis costs $1.99 up front. Equation Encyclopedia sells 9 in-app purchases, starting at $6.99 per month. Interactive Photosynthesis asks for nothing beyond the download.

Interactive Photosynthesis ships an update every 25 months, Equation Encyclopedia every 4 days. The most recent releases landed on September 10, 2026 and September 8, 2026 respectively.

## The numbers

| Metric | Interactive Photosynthesis | Equation Encyclopedia |
| --- | --- | --- |
| Price | $1.99 | **Free** |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 25 months | **Every 4 days** |
| Size | 183 MB | 451 MB |
| Requires iOS | **12.0** | 15.0 |
| Devices | iPad, Apple TV | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Ventura Educational Systems](https://appshunter.io/developer/371324172) | [SAMUEL MOYOSORE O ADEYIGA](https://appshunter.io/developer/1874179107) |

## What reviewers say

### Interactive Photosynthesis

[App page](https://appshunter.io/ios/app/interactive-photosynthesis/id1511209024)

**Features:** macOS Compatibility

**In-app purchases:** none


### Equation Encyclopedia

[App page](https://appshunter.io/ios/app/equation-encyclopedia/id6758647681)

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

**In-app purchases (9)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Plus Monthly | $6.99 | per month |
| Pro Monthly | $10.99 | per month |
| Ultra Monthly | $17.99 | per month |
| Plus Yearly | $49.99 | per year |
| Pro Yearly | $99.99 | per year |
| Ultra Yearly | $149.99 | per year |
| 10 Energy | $0.99 | one-time |
| 30 Energy | $2.99 | one-time |
| 100 Energy | $8.99 | one-time |


## Frequently asked questions

### Is Interactive Photosynthesis free?

Interactive Photosynthesis costs $1.99, with no in-app purchases.

### Is Equation Encyclopedia free?

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

### Do Interactive Photosynthesis or Equation Encyclopedia have ads?

Equation Encyclopedia shows ads; Interactive Photosynthesis does not.

### Which is updated more often, Interactive Photosynthesis or Equation Encyclopedia?

Interactive Photosynthesis ships an update every 25 months, and Equation Encyclopedia every 4 days. Most recently, Interactive Photosynthesis was updated on September 10, 2026 and Equation Encyclopedia on September 8, 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.*