# Stoichiometry vs Atom Structure

The clearest difference is update cadence: Stoichiometry at every 2 months against Atom Structure's every 41 months. Atom Structure's advantage is price ($1.99 vs $2.99) and iOS requirement (12.0 vs 17.1). On ads, in-app purchases and device support there is nothing between them.

Stoichiometry costs $2.99 and Atom Structure $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Stoichiometry ships an update every 2 months, Atom Structure every 41 months. The most recent releases landed on September 7, 2026 and September 10, 2026 respectively.

## The numbers

| Metric | Stoichiometry | Atom Structure |
| --- | --- | --- |
| Price | $2.99 | **$1.99** |
| Positive reviews | 50.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 2 months** | Every 41 months |
| Monetization | Paid | — |
| Size | 1 MB | 232 MB |
| Requires iOS | 17.1 | **12.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Roman Volinsky](https://appshunter.io/developer/977951850) | [VIRTUAL FILAMENTS PRIVATE LIMITED](https://appshunter.io/developer/1474217212) |

## What reviewers say

### Stoichiometry

[App page](https://appshunter.io/ios/app/stoichiometry/id1330949637)

This tool helps balance chemical reactions and calculate molar masses, moles, and actual masses of reactants and products. It supports various formula formats and can identify limiting reagents. Data can be sent to another app for gas phase calculations.

**Highlights:** Balance chemical reactions, Calculate molar masses, Determine moles and actual masses, Identify limiting reagents, Supports various formula formats, Integrates with Gas Phase Stoichiometry app

**Features:** Vision Pro support

**In-app purchases:** none


### Atom Structure

[App page](https://appshunter.io/ios/app/atom-structure-edutech-era/id1637054844)

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

**In-app purchases:** none


## Frequently asked questions

### Is Stoichiometry free?

Stoichiometry costs $2.99, with no in-app purchases.

### Is Atom Structure free?

Atom Structure costs $1.99, with no in-app purchases.

### Do Stoichiometry or Atom Structure have ads?

Neither Stoichiometry nor Atom Structure shows ads.

### Which is updated more often, Stoichiometry or Atom Structure?

Stoichiometry ships an update every 2 months, and Atom Structure every 41 months. Most recently, Stoichiometry was updated on September 7, 2026 and Atom Structure on September 10, 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.*