RPNPro vs Calccis
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.
Calccis
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Calccis is a reverse polish notation (RPN) calculator. It supports basic arithmetic, trigonometrical, logarithm and exponent calculations for real, fractional, and complex numbers. Degrees and radians can be used for trigonometrical functions. You can perform matrix calculations, too. There is an undo stack, which supports undoing and redoing the 100 latest operations. Calccis does not copy or mimic any existing physical calculators. However, the operation of the stack has been influenced by how the stack works in the 1990s Hewlett-Packard HP-48 family of calculators.
Screenshots
Verdict
The clearest difference is update cadence: Calccis at every 3 weeks against RPNPro's every 37 months. RPNPro's advantage is iOS requirement (9.1 vs 17.6). 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.
RPNPro ships an update every 37 months, Calccis every 3 weeks. The most recent releases landed on June 5, 2026 and September 12, 2026 respectively.
| Parameter | RPNPro | Calccis |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) — better | — |
| Positive reviews | 50.0% of reviews | — |
| Number of ratings | 1 — better | — |
| Update frequency | Every 37 months | Every 3 weeks — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | 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 | Jukka Aittola |
In-app purchases
RPNPro
No in-app purchases
Calccis
No in-app purchases
