# ThetaCalc vs HP

The clearest difference is rating: HP at 5.0 against ThetaCalc's 4.3. HP also leads on update cadence (every 11 days vs every 3 months). On price, review sentiment, ratings volume and ads there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

HP holds the better App Store score, 5.0 against 4.3. Both are backed by a comparable volume of ratings — 4 and 5 respectively. Written reviews split almost evenly too, at 100% and 100% positive.

ThetaCalc ships an update every 3 months, HP every 11 days. The most recent releases landed on June 1, 2026 and September 21, 2026 respectively.

## The numbers

| Metric | ThetaCalc | HP |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.3 (4 ratings)](https://appshunter.io/ios/app/thetacalc/id1521614636/reviews) | **[5.0 (5 ratings)](https://appshunter.io/ios/app/hp-35/id6738010641/reviews)** |
| Number of ratings | 4 | **5** |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 3 months | **Every 11 days** |
| Monetization | Free | Free |
| Size | 1 MB | 2 MB |
| Requires iOS | 17.6 | **17.2** |
| Devices | **iPhone, iPad** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Felix Stehli](https://appshunter.io/developer/1521614638) | [Enrique Haro](https://appshunter.io/developer/1778874870) |

## What reviewers say

### ThetaCalc

[App page](https://appshunter.io/ios/app/thetacalc/id1521614636)

This utility app provides a Reverse Polish Notation (RPN) calculator. Users can extend its functionality by programming custom functions and equations using JavaScript.

**Highlights:** Reverse Polish Notation (RPN) calculator, User-programmable functions, JavaScript equation support, Extensible functionality

**Features:** macOS Compatibility

**In-app purchases:** none


### 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


## Frequently asked questions

### Is ThetaCalc free?

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

### Is HP free?

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

### Which has better reviews, ThetaCalc or HP?

HP is rated higher. ThetaCalc averages 4.3 out of 5 from 4 ratings, while HP averages 5.0 from 5 ratings.

### Do ThetaCalc or HP have ads?

Neither ThetaCalc nor HP shows ads.

### Which is updated more often, ThetaCalc or HP?

ThetaCalc ships an update every 3 months, and HP every 11 days. Most recently, ThetaCalc was updated on June 1, 2026 and HP on September 21, 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.*