# allRPNCalc Calculator

> Advanced RPN calculator with multi-level stack and extensive function library. (iPhone/iPad app by Ernest Brock.)

- Source: https://appshunter.io/ios/app/allrpncalc-calculator/id289555909 (this page in markdown: same URL + `.md`)
- Developer: [Ernest Brock](https://appshunter.io/developer/289555912)
- Category: Finance, Productivity
- Price: $5.99
- Rating: 4.90/5 from 59 App Store ratings · 53 written reviews indexed
- Age rating: 4+
- Requires: iOS 11.0 · 2 MB
- Languages: English
- Released: 2019-02-01
- Data updated: 2026-06-10
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/allrpncalc-calculator/id289555909/reviews.md

## What is allRPNCalc Calculator?

allRPNCalc is a versatile calculator that uses the powerful Reverse Polish Notation logic system combined with an automated 4 level stack to compute answers to complex mathematical problems. The keyboard layout and display have been optimized for use on an iPhone,iPod Touch and iPad. Large keys with sound feed back give you typing confidence and the last function keyed is always displayed. Functions are logically laid out to eliminate multiple key entry for most problems.

Display: Results are displayed in fixed, fraction, scientific or engineering notation with from 0 to 14 significant digits displayed. In programmer’s mode hex, decimal, octal or binary (with windowing) can be displayed. Calculations are carried out in industry standard IEEE double format with 14+ significant digits and exponents ranging +/-308.

Math: +, -, ×, ÷, ln, log, e^x, 10^x, y^x, x², x³, 1/x, √x, ∛x, fraction part, integer part, absolute value, random, seed, mod

Trigonometry: sin, cos, tan, asin, acos, atan, sinh, cosh, tanh, asinh, acosh, atanh, to radians, to degrees, to rectangular, to polar, to hours, to hours minutes seconds, hours minutes seconds add and subtract, triangle solver, π, π/2. Trig functions can be computed in radians, degrees or gradians.

Statistics: sum plus, sum minus, mean, weighted mean, standard deviation, population standard deviation, linear estimate x, y and correlation coefficient, combination, permutation, factorial (gamma), percent, delta percent, percent of total

Programer’s functions: and, or, xor, not, shift left, shift right, rotate left, rotate right, word sizes 8, 16, 32, 48

Conversions: 47 world currencies and over 100 commonly used metric, english and other conversion factors used in scientific, engineering and financial calculations.

Financial: time value of money calculations, n, i, pv, pmt, fv, depreciation (straight line, sum-of-years, declining balance), bond price and yield to maturity, amortization, net present value, internal rate of return, up to 80 cash flows, days between dates, date plus days, rounding. 

Storage: 4 level automatic stack with lastX, exchange and roll down, 20 general purpose storage registers, register arithmetic +,-,×,÷ , 6 dedicated registers for statistics, 80 cash flow entries, 5 financial registers.

## Key features

- Reverse Polish Notation (RPN) logic
- Automated 4-level stack
- Extensive math, trig, and statistical functions
- Programmer's mode (hex, decimal, octal, binary)
- Currency and unit conversions
- Financial calculations (TVM, depreciation, amortization)

## Recent user reviews (10 of 53)

All indexed reviews: https://appshunter.io/ios/app/allrpncalc-calculator/id289555909/reviews.md

### 4/5 — Overall most functions work and some don’t work.

*2024-09-10*

I have tried to contact the technical support person for this application about several issues and have not heard back from him. The currency exchange converter is not working properly for a number of currencies such as Swiss francs (CHF) to US dollars. Negative numbers are miss handled and miss calculated going from Prog mode to Math mode. This application needs to reverse engineer how to handle negative numbers from the HP 16C calculator. In statistics mode when a logarithmic plot is made with a correlation of better than 0.999, the x axis approximation is severely miscalculated when the X,R button is pressed. Try this for yourself. The y axis approximation works nicely for the logarithmic curve plot. In the short time frame that I have been using this application I have found these issues. Most other features and functions are working perfectly well. There is probably more features that are not working which may make for another review by someone else. Overall this is a good application to experiment with and is worth the six dollars.

### 5/5 — Love this Calculator

*2023-12-07*

Had to have an RPN calculator, and this one has zero downsides. It like every HP in one. The developer is attentive to keeping it up-to-date with ios changes.

### 5/5 — Still the best RPN Calculator app out there!

*2023-11-06*

I grew up with an HP 35 and moved to the 11c. This app is superior to HP. So much more capability and usable functions. I have been using this RPN calculator since it came out many years ago and I love it! Great for engineering calculations, conversions and financial. This is a great product for a die hard engineer that grew up on RPN! Thanks for keeping it going!

### 5/5 — Best RPN Calc

*2023-01-21, version 4.2*

I grew up using the HP42s, which I loved. I have the phone app for the HP42 also but I use this app as my go to app. Easy to use with all of what I need within a few strokes.

### 5/5 — Better than HP!

*2022-08-05, version 4.2*

Didn’t think I’d ever say this, but this calculator is better than HP’s. Of course, it doesn’t have all the cool stuff built into a 15, for example, but for what it does it’s very thoughtfully designed and works conveniently well. I also like all the trivia and background sprinkled throughout the documentation, FAQ, etc. Not only is this a very well-designed and useful calculator, but it also educates you on some of the history and science behind implementing floating point math in a binary machine. I’m a very happy customer.

### 5/5 — Awesome

*2022-04-25, version 4.2*

Best smartphone calculator out there!

### 5/5 — Love the app

*2022-02-09, version 4.2*

Really nice app. Does a very good implementation of RPN, and has numerous useful functions. I use it every day.

### 5/5 — The best!!

*2021-11-07, version 4.2*

Hands down, the best calculator anywhere. If you’ve ever used an RPN calculator this is the one you need. If you haven’t used an RPN calculator, you should learn so you can use this one. 

Absolutely the best.

### 5/5 — Great RPN calculator!

*2021-07-18, version 4.2*

Beautifully implemented, with all the usual functions and many unexpected bonuses (e.g., currency conversions, 12c-like financial functions, stat plots with regression lines, etc.)

### 5/5 — Go-To Calculator

*2021-06-12, version 4.2*

A super all-in-one tool. I’ve used it every day for years. The conversion tool is especially helpful.

## Frequently asked questions about allRPNCalc Calculator

### What is Reverse Polish Notation (RPN)?

Reverse Polish Notation (RPN) is a mathematical notation where operators follow their operands. This means you enter numbers first, then the operation you want to perform. It often simplifies complex calculations by eliminating the need for parentheses and can be more efficient for experienced users.

### What types of calculations can this app perform?

This app supports a vast array of calculations, including basic arithmetic, logarithms, exponents, trigonometry (in radians, degrees, or gradians), statistics (mean, standard deviation, correlation), programmer functions (bitwise operations), currency conversions, and detailed financial calculations like time value of money, depreciation, and amortization.

### Is this app free to use?

Based on the provided information, this application is a paid app. There are no mentions of in-app purchases or advertisements, indicating a one-time purchase model for full functionality.

### What devices is this calculator compatible with?

The calculator is optimized for use on Apple devices, specifically mentioning compatibility with iPhone, iPod Touch, and iPad. This suggests it is an iOS application.

### How does the 4-level stack work?

The 4-level automatic stack is a core feature of RPN calculators. It allows you to store intermediate results automatically, making it easier to chain complex operations without manually managing memory. The stack typically holds the last four results, with functions operating on the top elements of the stack.

## Version history (last 5 releases)

### 4.2 — 2019-02-01

This app has been updated by Apple to display the Apple Watch app icon.

•Update for iOS11

### 4.0 — 2017-05-29

• iOS & 64 bit update
• Added ? key function help
• HTTPS security update
• All new vector high resolution graphics

### 3.02 — 2009-11-07

Add SI number formatting option

### 3.01 — 2009-08-11

Fixes a bug in reading previous settings files
iPhone 3.0 compatible

### 3.0 — 2009-07-24

• updated for iPhone 3.0
• improved email of amort table
• improved currency rate downloads

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## More apps by Ernest Brock

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- [12Calc](https://appshunter.io/ios/app/12calc/id780780002)

All apps by Ernest Brock: https://appshunter.io/developer/289555912

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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.*