# OPie RPN Calculator — Sci, Graph, Stats, Lin EQ

> RPN calculator with equation plotter, statistics, linear solver, and unit converter. (iPhone/iPad app by Andrew Swenson.)

- Source: https://appshunter.io/ios/app/opie-rpn-calculator/id1559116337 (this page in markdown: same URL + `.md`)
- Developer: [Andrew Swenson](https://appshunter.io/developer/1558926423)
- Category: Utilities, Productivity
- Price: Free with in-app purchases
- Rating: 4.90/5 from 8 App Store ratings
- Age rating: 4+
- Requires: iOS 14.3 · 8 MB
- Languages: American English, Chinese (Simplified, China)
- Released: 2021-03-19
- Data updated: 2026-06-10
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/opie-rpn-calculator/id1559116337/reviews.md

## What is OPie RPN Calculator?

This is a combination RPN scientific calculator, RPN basic calculator, equation plotter, one-button statistics, linear equation solver, and unit converter.

After entering a lot of numbers onto the stack (useful for entering data for statistics), you can quickly remove or reorder those numbers by going into the E-Stack Editor.

The linear equation solver will solve up to 6 simultaneous equations.

Easily plot up to 8 equations from the Graph page.  

The unit converter page converts length, area, temperature, volume, weight, angle, digital storage, energy, pressure, force, time, electric current, speed, and luminance.

Note: swipe down on the keyboard to hide the tab bar and swipe up to display the tab bar.

## Key features

- RPN scientific and basic calculator
- Equation plotter (up to 8 equations)
- One-button statistics
- Linear equation solver (up to 6 simultaneous)
- Extensive unit converter
- E-Stack Editor for data management

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Remove Ads | $2.99 | one-time |



## Frequently asked questions about OPie RPN Calculator

### What is OPie RPN Calculator used for?

OPie RPN Calculator is a multi-functional utility that serves as an RPN scientific calculator, basic calculator, equation plotter, statistics tool, linear equation solver, and unit converter.

### What devices does OPie RPN Calculator support?

OPie RPN Calculator is available for iPhone, iPad, and iPod touch devices.

### How many equations can be plotted with OPie RPN Calculator?

You can easily plot up to 8 equations simultaneously from the Graph page within OPie RPN Calculator.

### Can OPie RPN Calculator solve multiple linear equations?

Yes, the linear equation solver in OPie RPN Calculator can solve up to 6 simultaneous linear equations.

### What types of units can OPie RPN Calculator convert?

OPie RPN Calculator features a comprehensive unit converter that includes length, area, temperature, volume, weight, angle, digital storage, energy, pressure, force, time, electric current, speed, and luminance.

### How is the stack managed in OPie RPN Calculator?

For managing large amounts of numbers, especially for statistics, OPie RPN Calculator includes an E-Stack Editor that allows you to quickly remove or reorder numbers on the stack.

### What is the age rating for OPie RPN Calculator?

OPie RPN Calculator has an age rating of 4+, making it suitable for a wide range of users.

### When was OPie RPN Calculator last updated?

The latest version of OPie RPN Calculator was released on November 18, 2021.

## Version history (last 5 releases)

### 3.0 — 2021-11-18

-fixed graph mode plot display when using radians

### 2.9 — 2021-11-03

-minor layout changes
-improved graph mode display of multiple graphs
-convert page:  second depression of clear button clears entire display.  Note that the Unit Convertor included in RPN calculator is for the basic version only.  There is a stand alone version at the app store where you can purchase an expansion pack.

### 2.8 — 2021-10-10

improved: various items on the plot page including removing the numbers on the right hand axis.
fixed: Info Page English version (the text had disappeared)
removed: the tabBar from the info page (the back arrow is how you navigate away from the info page

### 2.7 — 2021-10-09

fixed: exponent (^) button on plot page.

### 2.6 — 2021-09-21

added: In-App Purchase to remove advertising (go to the information page (i) on the App)
added: images to the tab bar.
added: information button to the linear equation page.
fixed: translations on linear equation page
fixed: iPhone rotation issue (This app is not supposed to display in landscape on an iPhone)

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## More apps by Andrew Swenson

- [OPie Isentropic Calculator](https://appshunter.io/ios/app/opie-isentropic-calculator/id1558926421)
- [OPie RetireFIRE](https://appshunter.io/ios/app/opie-retirefire/id1562734440)
- [OPie Unit Converter](https://appshunter.io/ios/app/opie-unit-converter/id1570481314)
- [OPie Tip Calc](https://appshunter.io/ios/app/opie-tip-calc/id1570900875)
- [OPie Mohr's Circle](https://appshunter.io/ios/app/opie-mohrs-circle/id1581023550)

All apps by Andrew Swenson: https://appshunter.io/developer/1558926423

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-10.*