# Formula & Units vs Periodic

The clearest difference is price: Periodic at Free against Formula & Units's $3.99. Formula & Units's advantage is ads (none vs shown). On update cadence, in-app purchases, device support and iOS requirement there is nothing between them.

Periodic is free to download; Formula & Units costs $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Formula & Units ships an update every 2 months, Periodic every 5 weeks. The most recent releases landed on August 20, 2026 and May 16, 2026 respectively.

## The numbers

| Metric | Formula & Units | Periodic |
| --- | --- | --- |
| Price | $3.99 | **Free** |
| In-app purchases | No | No |
| Ads | **No** | Yes |
| Update frequency | Every 2 months | **Every 5 weeks** |
| Size | 1 MB | 35 MB |
| Requires iOS | 16.0 | **15.1** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Roman Volinsky](https://appshunter.io/developer/977951850) | [Om Prakash Chapagain](https://appshunter.io/developer/1618620262) |

## What reviewers say

### Formula & Units

[App page](https://appshunter.io/ios/app/formula-and-units/id1255813016)

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

**In-app purchases:** none


### Periodic

[App page](https://appshunter.io/ios/app/periodic-table-elements/id1628647298)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Formula & Units free?

Formula & Units costs $3.99, with no in-app purchases.

### Is Periodic free?

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

### Do Formula & Units or Periodic have ads?

Periodic shows ads; Formula & Units does not.

### Which is updated more often, Formula & Units or Periodic?

Formula & Units ships an update every 2 months, and Periodic every 5 weeks. Most recently, Formula & Units was updated on August 20, 2026 and Periodic on May 16, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*