RPNPro vs ThetaCalc
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
RPNPro
This calculator utilizes Reverse Polish Notation (RPN) for input, mirroring the functionality of classic HP calculators. It features a four-level stack with X, Y, Z, and T registers, displaying the X register in decimal, hexadecimal, and binary.
- Reverse Polish Notation (RPN) input
- Four-level stack (X, Y, Z, T registers)
- Decimal, hexadecimal, and binary display
- Modeled after HP calculators
- Designed for software engineers
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RPNPro is a calculator for software engineers. RPNPro uses RPN (Reverse Polish Notation) as an input scheme. It is based on the same four level stack model as provided by the original HP (Hewlett-Packard) calculators, featuring X, Y, Z and T registers. The contents of the X register are always shown in decimal, hexadecimal and binary notation.
ThetaCalc
This utility app provides a Reverse Polish Notation (RPN) calculator. Users can extend its functionality by programming custom functions and equations using JavaScript.
- Reverse Polish Notation (RPN) calculator
- User-programmable functions
- JavaScript equation support
- Extensible functionality
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ThetaCalc is a RPN (Reverse Polish Notation) calculator which can be extended by functions and equations programmed by the user in JavaScript.
Screenshots
Verdict
The clearest difference is review sentiment: ThetaCalc at 100% against RPNPro's 50%. ThetaCalc also leads on update cadence (every 3 months vs every 37 months) and ratings volume (4 vs 1). RPNPro's advantage is rating (5.0 vs 4.3) and iOS requirement (9.1 vs 17.6). On price, ads, in-app purchases and monetization model 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.
RPNPro holds the better App Store score, 5.0 against 4.3. Both are backed by a comparable volume of ratings — 1 and 4 respectively. Written reviews complicate that: 50% of RPNPro's written reviews are positive against 100% of ThetaCalc's, so the app with the better star average is not the one people write more warmly about.
RPNPro ships an update every 37 months, ThetaCalc every 3 months. The most recent releases landed on September 28, 2026 and October 1, 2026 respectively.
| Parameter | RPNPro | ThetaCalc |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) — better | 4.3 (4 ratings) |
| Positive reviews | 50.0% of reviews | 100.0% of reviews — better |
| Number of ratings | 1 | 4 — better |
| Update frequency | Every 37 months | Every 3 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 9.1 — better | 17.6 |
| Further details — not scored | ||
| Size | 1 MB | 1 MB |
| Age rating | 4+ | 4+ |
| Developer | Felix Meier | Felix Stehli |
Customer experience
RPNPro
ThetaCalc
In-app purchases
RPNPro
No in-app purchases
ThetaCalc
No in-app purchases
