# HP vs Modern RPN

The clearest difference is price: HP at Free against Modern RPN's $2.99. HP also leads on ratings volume (59 vs 1) and iOS requirement (17.2 vs 26.2). Modern RPN's advantage is rating (5.0 vs 4.6) and update cadence (every 5 days vs every 11 days). On review sentiment, ads, in-app purchases and device support there is nothing between them.

HP is free to download; Modern RPN costs $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Modern RPN holds the better App Store score, 5.0 against 4.6. That said, the two scores are not equally well evidenced: HP has 59 ratings behind it against 1, so its average is the more settled of the two. Written reviews split almost evenly too, at 100% and 100% positive.

HP ships an update every 11 days, Modern RPN every 5 days. The most recent releases landed on October 27, 2026 and October 28, 2026 respectively.

## The numbers

| Metric | HP | Modern RPN |
| --- | --- | --- |
| Price | **Free** | $2.99 |
| Rating | [4.6 (59 ratings)](https://appshunter.io/ios/app/hp-35/id6738010641/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/modern-rpn/id6760340697/reviews)** |
| Number of ratings | **59** | 1 |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 11 days | **Every 5 days** |
| Monetization | **Free** | Paid |
| Size | 2 MB | 2 MB |
| Requires iOS | **17.2** | 26.2 |
| Devices | iPhone | **iPhone, iPad** |
| Age rating | 4+ | 4+ |
| Developer | [Enrique Haro](https://appshunter.io/developer/1778874870) | [Kevin Flathers](https://appshunter.io/developer/1883973737) |

## What reviewers say

### HP

[App page](https://appshunter.io/ios/app/hp-35/id6738010641)

Emulates classic Hewlett Packard RPN scientific calculators from the 1970s. Experience the original HP-35, HP-45, and HP-21 models on your iPhone.

**Highlights:** RPN calculator emulation, HP-35 model, HP-45 model, HP-21 model, Classic scientific calculator interface

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

**In-app purchases:** none


### Modern RPN

[App page](https://appshunter.io/ios/app/modern-rpn/id6760340697)

A minimalist reverse Polish notation calculator for iOS devices. It offers Standard, Binary, and Hex modes for quick calculations and programmer-friendly conversions, featuring a clean interface and a 4-level stack.

**Highlights:** Reverse Polish Notation (RPN) input, Standard, Binary, and Hex modes, 4-level visible stack, Calculation history, Saved session state, Clean dark interface

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is HP free?

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

### Is Modern RPN free?

Modern RPN costs $2.99, with no in-app purchases.

### Which has better reviews, HP or Modern RPN?

Modern RPN is rated higher. HP averages 4.6 out of 5 from 59 ratings, while Modern RPN averages 5.0 from 1 ratings.

### Do HP or Modern RPN have ads?

Neither HP nor Modern RPN shows ads.

### Which is updated more often, HP or Modern RPN?

HP ships an update every 11 days, and Modern RPN every 5 days. Most recently, HP was updated on October 27, 2026 and Modern RPN on October 28, 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.*