# RPN Calc vs lithium connect

The clearest difference is price: lithium connect at Free against RPN Calc's $0.99. lithium connect also leads on iOS requirement (13.0 vs 16.0). On update cadence, ads, in-app purchases and device support there is nothing between them.

lithium connect is free to download; RPN Calc costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Both ship on a similar rhythm, roughly every 3 months. Both last shipped on October 31, 2026.

## The numbers

| Metric | RPN Calc | lithium connect |
| --- | --- | --- |
| Price | $0.99 | **Free** |
| Rating | **[4.0 (6 ratings)](https://appshunter.io/ios/app/rpn-calc/id285002799/reviews)** | — |
| Number of ratings | **6** | — |
| Positive reviews | 37.9% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 3 months | Every 3 months |
| Monetization | Free | — |
| Size | 3 MB | 30 MB |
| Requires iOS | 16.0 | **13.0** |
| Devices | **iPhone, iPad, Apple Watch** | iPhone, iPod |
| Age rating | +4 | 4+ |
| Developer | [James Mattis](https://appshunter.io/developer/285002802) | [军 吴](https://appshunter.io/developer/1855893545) |

## What reviewers say

### RPN Calc

[App page](https://appshunter.io/ios/app/rpn-calc/id285002799)

This app provides a straightforward reverse Polish notation (RPN) calculator experience, inspired by classic HP models. It offers a clean interface with large buttons for quick calculations on iPhone, iPad, and Apple Watch, along with a convenient Today Extension for immediate access.

**Highlights:** Reverse Polish Notation (RPN) input, Clean, simple interface, Large, easy-to-press buttons, iPhone, iPad, and Apple Watch support, Today Extension for quick access

**Features:** macOS Compatibility, Apple Watch app, Vision Pro support

**In-app purchases:** none


### lithium connect

[App page](https://appshunter.io/ios/app/lithium-connect/id6757992562)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is RPN Calc free?

RPN Calc costs $0.99, with no in-app purchases.

### Is lithium connect free?

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

### Do RPN Calc or lithium connect have ads?

Neither RPN Calc nor lithium connect shows ads.

### Which is updated more often, RPN Calc or lithium connect?

RPN Calc ships an update every 3 months, and lithium connect every 3 months. Most recently, RPN Calc was updated on October 31, 2026 and lithium connect on October 31, 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.*