Comparison

Calx vs RPN

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

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.

Highlights
  • Reverse Polish Notation (RPN)
  • Gestural interaction
  • Multiple keypads (basic, scientific, statistical)
  • Customizable fonts and colors
  • Guided tutorial
Features
Read full description

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.

About

RPN

Features
Read full description

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

Calx3 screens
RPN4 screens

Verdict

The call

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

CostPrice · In-app purchases · Ads · Monetization

Calx costs $0.99 and RPN $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

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.

Scorecard3 real differences · 7 level
Calx versus RPN: the parameters behind the verdict, then further details
ParameterCalxRPN
Price$0.99 — better$4.99
Rating5.0 (2 ratings) — better—
Positive reviews100.0% of reviews—
Number of ratings2 — better—
Update frequencyEvery 24 monthsEvery 7 months — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaid—
DevicesiPhone, iPodiPhone, iPad, Mac — better
Requires iOS12.0 — better16.6
Further details — not scored
Size4 MB1 MB
Age rating4+4+
DeveloperDaniel ClellandSteven Davies

In-app purchases

None

Calx

No in-app purchases

None

RPN

No in-app purchases

Questions

Is Calx free?
Calx costs $0.99, with no in-app purchases.
Is RPN free?
RPN costs $4.99, with no in-app purchases.
Do Calx or RPN have ads?
Neither Calx nor RPN shows ads.
Which is updated more often, Calx or RPN?
Calx ships an update every 24 months, and RPN every 7 months. Most recently, Calx was updated on August 12, 2026 and RPN on August 2, 2026.

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