# Periodic vs DrPhos' Stoichiometry

The clearest difference is in-app purchases: Periodic at none against DrPhos' Stoichiometry's 11. Periodic also leads on iOS requirement (15.1 vs 17.2). DrPhos' Stoichiometry's advantage is price ($0.99 vs $1.99). On update cadence, ads and device support there is nothing between them.

Periodic costs $1.99 and DrPhos' Stoichiometry $0.99 up front. DrPhos' Stoichiometry sells 11 one-off in-app purchases. Periodic asks for nothing beyond the download.

Periodic ships an update every 5 weeks, DrPhos' Stoichiometry every 3 weeks. The most recent releases landed on August 16, 2026 and September 20, 2026 respectively.

## The numbers

| Metric | Periodic | DrPhos' Stoichiometry |
| --- | --- | --- |
| Price | $1.99 | **$0.99** |
| Rating | — | **[5.0 (1 ratings)](https://appshunter.io/ios/app/drphos-stoichiometry/id6475633178/reviews)** |
| Number of ratings | — | **1** |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 5 weeks | **Every 3 weeks** |
| Monetization | — | Paid |
| Size | 31 MB | 15 MB |
| Requires iOS | **15.1** | 17.2 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Om Prakash Chapagain](https://appshunter.io/developer/1618620262) | [Monte L Helm](https://appshunter.io/developer/1715082616) |

## What reviewers say

### Periodic

[App page](https://appshunter.io/ios/app/periodic-table-elements-pro/id1628646759)

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

**In-app purchases:** none


### DrPhos' Stoichiometry

[App page](https://appshunter.io/ios/app/drphos-stoichiometry/id6475633178)

This tool simplifies solving chemical reaction problems by allowing users to input balanced equations and identify known and unknown compounds. It instantly calculates moles and mass, assisting students with various stoichiometry challenges.

**Highlights:** Mole, mass, and volume conversions, Balanced chemical equation support, Compound selection, Limiting reactant detection, High school and college chemistry focus

**Features:** macOS Compatibility

**In-app purchases (11)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Significant Figures Counter | $0.99 | one-time |
| Science Calculator | $0.99 | one-time |
| Quadratic Equation Solver | $0.99 | one-time |
| Kinetics | $0.99 | one-time |
| Molar Mass Calculator | $0.99 | one-time |
| General Chemistry Naming | $0.99 | one-time |
| Ionic Compound Builder | $0.99 | one-time |
| Solution Concentrations | $0.99 | one-time |
| Reaction Balancer | $0.99 | one-time |
| pH Calculator | $0.99 | one-time |
| Stoichiometry | $0.99 | one-time |


## Frequently asked questions

### Is Periodic free?

Periodic costs $1.99, with no in-app purchases.

### Is DrPhos' Stoichiometry free?

DrPhos' Stoichiometry costs $0.99, and also offers in-app purchases.

### Do Periodic or DrPhos' Stoichiometry have ads?

Neither Periodic nor DrPhos' Stoichiometry shows ads.

### Which is updated more often, Periodic or DrPhos' Stoichiometry?

Periodic ships an update every 5 weeks, and DrPhos' Stoichiometry every 3 weeks. Most recently, Periodic was updated on August 16, 2026 and DrPhos' Stoichiometry on September 20, 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.*