Calx vs RPN
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Calx
This calculator app utilizes Reverse Polish Notation (RPN) for efficient calculations by manipulating numbers on a stack. It offers a guided tutorial, gestural interaction, multiple keypads with various functions, and customization options for fonts and colors.
- Reverse Polish Notation (RPN)
- Gestural interaction
- Multiple keypads (basic, scientific, statistical)
- Customizable fonts and colors
- Guided tutorial
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CALX is an RPN calculator — a calculator designed to work with a list of numbers. This means that instead of just typing an equation into your calculator, you push numbers onto a stack, and then apply operations to the lowermost numbers in the stack. It's bizarre, but it makes sense once it clicks. If this all sounds confusing, don't worry! CALX comes with a guided tutorial which will get you up to speed in three minutes. Features: • Gestural interaction: Manipulate your data with simple, intuitive gestures. • Multiple keypads: CALX features an array of basic, scientific, and statistical functions. • Customization: Select from different fonts and colours to find a combination that works for you.
RPN
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The basic four function calculator displays numbers in fixed format. The scientific calculator has 75 built-in functions covering logarithms, powers, roots, trigonometric, date, time, memory operations, statistics, and probabilities and up to four user defined macro functions. It displays numbers in user configurable fixed, scientific, or engineering formats. The user configurable calculator has sixteen user configurable function buttons that can each be assigned two functions from 75 built-in functions and access an unlimited number of user defined macro functions. It displays numbers in user configurable fixed, scientific, or engineering formats. The programmer’s calculator has a hexadecimal keypad and displays numbers in user configurable hexadecimal format. It has four basic mathematics, six bitwise, and two shift functions. All calculators share an operation history display for ease of reviewing computations and extensive in-app help documentation. Numbers can be copied to and pasted from the clipboard for ease of use with other applications.
Screenshots
Verdict
The clearest difference is price: Calx at $0.99 against RPN's $4.99. Calx also leads on iOS requirement (12.0 vs 16.6). RPN's advantage is update cadence (every 7 months vs every 24 months). On 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
Calx costs $0.99 and RPN $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Calx ships an update every 24 months, RPN every 7 months. The most recent releases landed on August 12, 2026 and August 2, 2026 respectively.
| Parameter | Calx | RPN |
|---|---|---|
| Price | $0.99 — better | $4.99 |
| Rating | 5.0 (2 ratings) — better | — |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 2 — better | — |
| Update frequency | Every 24 months | Every 7 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | — |
| Devices | iPhone, iPod | iPhone, iPad, Mac — better |
| Requires iOS | 12.0 — better | 16.6 |
| Further details — not scored | ||
| Size | 4 MB | 1 MB |
| Age rating | 4+ | 4+ |
| Developer | Daniel Clelland | Steven Davies |
In-app purchases
Calx
No in-app purchases
RPN
No in-app purchases









