InterCalc vs RPNu
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
InterCalc
This app performs linear interpolation using a set of X-Y values to define a relationship. It can calculate values based on defined points, useful for tasks like converting pressure readings to fluid volumes in containers or performing simple unit conversions.
- Linear interpolation of X-Y values
- Defines arbitrary functions from data points
- Calculates fluid volume from pressure readings
- Performs unit conversions (e.g., temperature, speed)
- Supports custom data sets
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This application is designed to linearly interpolate a value given a set of X-Y values that define a relationship. The X-Y values can be as simple as two points that specify a simple line, or they can be a set of points that specifies an arbitrary function. One use of this program is to calculate the amount of fluid in a container given a pressure reading at the bottom of the tank. Typically this situation results in several pressure readings and corresponding volume ( gallons, liters ) readings as the tank is being filled. Once the pressure measuring device is so calibrated, pressure readings can then be converted to gallon or liter values. Other uses include simple conversions between Fahrenheit and Celsius, or between kph and mph.
RPNu
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RPNu is a calculator that makes crunching numbers easier than it’s algebraic equivalent. RPN stand for Reverse Polish Notation (The ‘u’ stands for universal, meaning it runs on both the iPad and iPhone.) and is the numeric evaluation method used for this app. RPN, I feel, is far superior to the algebraic method and once learned you will never want to use the algebraic again. This calculator has all the normal mathematical function, but also contains a host of other functions that you may find very useful. Space is limited in this description but here are the highlights: Help: There is extensive help to aid the user in determining how to use this app. It is also context sensitive. Programable: You can write your own programs and there are many tools to aid you in doing this. Graphics: You can graph equations and there are several modes to cover almost all requirements. A universal converter that you will find very useful. Matrix arithmetic (determinate, invert, add, subtract and multiply). Date calculator and an hours calculator with moon phase display. Elements and periodic table information. Combinations and permutations calculator Equation integration and root finder. Amortization with many useful functions. Mapping function that allows you to determine distance between points and other functions. Hyperbolic functions. Hexadecimal, Octal, and Binary modes. Barometer function showing QNE and QNH. A compass that not only shows magnetic and true north, but also shows the address you are at. This app includes extensive support for a Bluetooth keyboard. Also, extensive support is given to export your calculations to either email or the universal clipboard.
Screenshots
Verdict
The clearest difference is update cadence: RPNu at every 2 months against InterCalc's every 11 months. RPNu also leads on iOS requirement (15.0 vs 18.6). On price, ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
InterCalc ships an update every 11 months, RPNu every 2 months. The most recent releases landed on October 17, 2026 and October 12, 2026 respectively.
| Parameter | InterCalc | RPNu |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) — better | — |
| Number of ratings | 1 — better | — |
| Update frequency | Every 11 months | Every 2 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | — |
| Devices | iPhone, iPad | iPhone, iPad, iPod — better |
| Requires iOS | 18.6 | 15.0 — better |
| Further details — not scored | ||
| Size | 1 MB | 49 MB |
| Age rating | 4+ | 4+ |
| Developer | River Rock Logic | Scott Johnson |
In-app purchases
InterCalc
No in-app purchases
RPNu
No in-app purchases









