# Calx vs RPN

The clearest difference is price: Calx at $0.99 against RPN's $4.99. Calx also leads on iOS requirement (12.0 vs 16.6). RPN's advantage is update cadence (every 7 months vs every 24 months). On ads, in-app purchases and device support there is nothing between them.

Calx costs $0.99 and RPN $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Calx ships an update every 24 months, RPN every 7 months. The most recent releases landed on August 12, 2026 and August 2, 2026 respectively.

## The numbers

| Metric | Calx | RPN |
| --- | --- | --- |
| Price | **$0.99** | $4.99 |
| Rating | **[5.0 (2 ratings)](https://appshunter.io/ios/app/calx-stack-calculator/id928929230/reviews)** | — |
| Number of ratings | **2** | — |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 24 months | **Every 7 months** |
| Monetization | Paid | — |
| Size | 4 MB | 1 MB |
| Requires iOS | **12.0** | 16.6 |
| Devices | iPhone, iPod | **iPhone, iPad, Mac** |
| Age rating | 4+ | 4+ |
| Developer | [Daniel Clelland](https://appshunter.io/developer/912177584) | [Steven Davies](https://appshunter.io/developer/1705785558) |

## What reviewers say

### Calx

[App page](https://appshunter.io/ios/app/calx-stack-calculator/id928929230)

This calculator app utilizes Reverse Polish Notation (RPN) for efficient calculations by manipulating numbers on a stack. It offers a guided tutorial, gestural interaction, multiple keypads with various functions, and customization options for fonts and colors.

**Highlights:** Reverse Polish Notation (RPN), Gestural interaction, Multiple keypads (basic, scientific, statistical), Customizable fonts and colors, Guided tutorial

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

**In-app purchases:** none


### RPN

[App page](https://appshunter.io/ios/app/rpn-calc/id6464329997)

**Features:** Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Calx free?

Calx costs $0.99, with no in-app purchases.

### Is RPN free?

RPN costs $4.99, with no in-app purchases.

### Do Calx or RPN have ads?

Neither Calx nor RPN shows ads.

### Which is updated more often, Calx or RPN?

Calx ships an update every 24 months, and RPN every 7 months. Most recently, Calx was updated on August 12, 2026 and RPN on August 2, 2026.

---

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