# RPN-25 CE — Highly popular 1975 calculator

> Photo-realistic simulation of the HP-25 scientific calculator with advanced features. (iPhone/iPad app by CuVee Software.)

- Source: https://appshunter.io/ios/app/rpn-25-ce/id1529311398 (this page in markdown: same URL + `.md`)
- Developer: [CuVee Software](https://appshunter.io/developer/424873503)
- Category: Utilities, Education
- Price: $2.99
- Rating: 4.60/5 from 9 App Store ratings · 5 written reviews indexed
- Age rating: 4+
- Requires: iOS 12.0 · 28 MB
- Languages: American English
- Released: 2020-09-02
- Data updated: 2026-08-26
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/rpn-25-ce/id1529311398/reviews.md

## What is RPN?

RPN-25 CE is a photo-realistic simulation of Hewlett-Packard's highly popular scientific calculator HP-25 for the iPhone. Produced from August 1975 through 1978, it was the "Squash" member of the second-generation HP calculators known as the "Woodstock" series.

It was also the first programmable calculator costing less than $200.

RPN-25 CE simulates the HP-25C version released in July 1976. Its major improvement in that update was "Continuous Memory".

While the simulator works just like the original calculator, a number of carefully designed extensions make it massively more powerful.


Features:

• Photo-realistic look
• Programmable (99 or 999 steps), subroutines, conditional loops, branching
• Insert and delete steps with automatic address correction
• 15 user-defined function keys of up to 6 characters each, redefinable under program control
• Programmable text messages
• Program Auto-Start option upon loading
• 100 symbolic labels
• 100 visible registers, "non-volatile", with unrestricted store/recall arithmetic
• 100 flags, visible at a glance
• Single-step constants
• Program comments
• Program library with more than 150 programs pre-installed
• More than 270 functions and operations not available on the HP-25
• 100 sounds built-in
• Much faster than the original
• "Live" register view supporting user interaction (run/stop, single-stepping)
• "Live" stack view
• Thousands separator (optional)
• High-contrast display (optional)
• Selectable pause length (up to a day)
• Program listing view with program title and description
• Program library view
• Store, name and retrieve any number of programs
• Sharing: Files, iCloud Drive, e-mail, AirDrop, Dropbox, copy, paste, print
• Import and run RPN-32 CE and GO-25 programs
• Run a large number of HP-41 programs with little or no changes
• Clock display (AM/PM or 24h)
• Supports Dark Mode

Calculator functions:

• Statistics, including clearing statistics registers only
• Factorial for arbitrary arguments 
• Trigonometric functions (degrees, radians, grads)
• Polar/rectangular conversions
• Inverse, square root, logarithm, exponential, Pi
• Percentage
• Storage arithmetic (store and recall)
• Extended stack operations
• Low-battery warning
• Sound alerts
• ..and many, many more

Details: cuveesoft.ch/rpn25

## Key features

- Photo-realistic simulation
- Programmable (99/999 steps)
- 15 user-defined function keys
- 100 symbolic labels
- 100 visible registers
- Program library with 150+ programs
- Over 270 functions

## Recent user reviews (5 of 5)

All indexed reviews: https://appshunter.io/ios/app/rpn-25-ce/id1529311398/reviews.md

### 5/5 — Brillant Emulator

*2026-01-31*

This was my first programmable calculator at age 14. The possibilities and programming examples really changed my life. This app is a remarkable good reproduction of this great piece of hardware. Thanks for making it so realistic and versatile!

### 5/5 — Fantastic app

*2024-11-27*

I missed my Hp-25 calculator so much these past 40 years. It was my beloved tool when I was an Engineering student at Laval University in Quebec. This app makes it possible to experience this great calculator again! It works exactly like the one I had, in Vintage mode. What great memories. Many thanks to the developer!

### 1/5 — Programming not currently working

*2023-07-08*

Wasted 3$ on this app. Programming is full of problems like GTO addresses that come up incorrectly. Don’t buy ! Not till it’s fixed anyway!

### 5/5 — Best app ever

*2022-04-15*

Best app ever! Excellent and realistic HP 25 emulation. I had this calculator when I was a teenager, and it prompted my 20-year career in software engineering. Thank you so much for the trip down memory lane. And I actually prefer using this calculator app than iOS’s native calculator app! Thank you.

### 5/5 — Outstanding app, great developer!!

*2020-09-04*

I have been using the HP25 hardware calc since I purchased it in ‘76. It still works to this day. This app is exactly what I have been waiting for, even better than the real calculator. Thanks Willy for building this, your apps are the best!!!

## Frequently asked questions about RPN

### What is RPN-25 CE?

RPN-25 CE is a photo-realistic simulation of the Hewlett-Packard HP-25 scientific calculator, released in 1975. It replicates the original functionality while adding modern extensions for enhanced usability on iOS devices.

### Is RPN-25 CE free?

RPN-25 CE is a paid application. It is available for a one-time purchase price of $2.99.

### Does RPN-25 CE have ads?

No, RPN-25 CE is ad-free. The application does not contain any advertisements, providing an uninterrupted user experience.

### What devices does RPN-25 CE support?

RPN-25 CE is designed for iPhone and iPod Touch devices. It also supports Dark Mode for a comfortable viewing experience.

### How often is RPN-25 CE updated?

The latest version of RPN-25 CE is 5.4, last updated on October 16, 2025. Updates typically include new features, bug fixes, and performance improvements.

### Can RPN-25 CE import programs from other calculators?

Yes, RPN-25 CE can import and run programs from RPN-32 CE and GO-25. It can also run a large number of HP-41 programs with minimal or no modifications.

### What are the programming capabilities of RPN-25 CE?

RPN-25 CE offers extensive programming features, including 99 or 999 steps, subroutines, conditional loops, branching, and 100 symbolic labels. It also supports programmable text messages and program comments.

### What is the age rating for RPN-25 CE?

RPN-25 CE has an age rating of 4+. This indicates it is suitable for users of all ages, with no mature content.

## Version history (last 5 releases)

### 5.4 — 2025-10-16

• Improved compatibility with iPhone Air and iOS 26.

### 5.3 — 2025-07-28

Non-volatile stack: when reloading the app, the stack is now restored along with all registers.

### 5.2 — 2025-04-21

• Faster startup – no delay until the first button press is recognized after switching on.

• The instructions _GTO 60 and _GSB 60 now appear correctly aligned in the program listing.

### 5.1 — 2024-10-19

• The instruction "ERROR nn" with nn = 99 will cause the display to blink rapidly three times.

Bug Fix:

• In the sample program "41-Curve Fitting (Kolb)", the equation for curve 3 ("Combined Linear and Hyperbolic") was incorrectly shown as y = a + b/x + c/x instead of y = a + b•x + c/x. Tap "Restore Sample Progs" in the program list to see the change.

### 5.0 — 2024-07-02

• New sample program "Holidays multilingual" shows the date of Ash Wednesday, Easter, Ascension, Whitsun, and Corpus Christi for any year in the range 1583 to 4099 in three languages (English, Spanish, German).

• New sample program "41-Curve Fitting (Kolb)" automatically finds the best fitting curve (out of 20) for a given set of data points.

• Toggle LED vs. High-Contrast display: f double-tap display

• Toggle thousand separators on/off: f triple-tap display

• Setting flag 41 causes ∑+ and ∑- to use the HP-41 locations of statistical registers.

• Added warning when attempting to alter a Sample Program.

• The trig mode indicator DEG is switched off after the selected "Pause Length".

• "FC?S nn" (renamed to "FC?S/C nn") acts as "FC?C nn" if flag 41 is set.


Changed instruction:

• "∑SWAP41 nn" (was ∑SWAP41)
Swaps the current RPN-25 statistics data block with the HP-41-compatible block at the location Rnn.


Bug Fixes:

• Calling up the Rydberg constant in the sample program CODATA 2018• would cause a crash.
• Alignment of messages (MSG,MSGP,MSGP) could be incorrect in some cases.

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## More apps by CuVee Software

- [RPN-45 HD](https://appshunter.io/ios/app/rpn-45-hd/id424873500)
- [RPN-70 HD](https://appshunter.io/ios/app/rpn-70-hd/id436127144)
- [Smart Sudoku](https://appshunter.io/ios/app/smart-sudoku/id457564906)
- [Vintage-45](https://appshunter.io/ios/app/vintage-45/id506402272)
- [RPN-45 SD](https://appshunter.io/ios/app/rpn-45-sd/id509923051)
- [RPN-67 NP](https://appshunter.io/ios/app/rpn-67-np/id603100249)

All apps by CuVee Software: https://appshunter.io/developer/424873503

## Related topics

[cuvee software](https://appshunter.io/ios/topics/cuvee-software)

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-26.*